The dashboard flickers 16:54 as we kill the engine and climb out of the car. The clouds are low and dark, the air is intoxicatingly fresh, and the sun – steadily lowering itself towards the hills out west – sits like a muffled yellow-white orb through the gloom, testing the clouds' resolve as it pries for holes to burst through.

After just shy of seven hours driving, we're standing in front of our home for the night: a wood-panelled bothy in a field at Brockloch Farm in Galloway – a vast region made up of miles of agricultural and forestry land just over the Scottish border from Carlisle. This morning, we queued for the Blackwall Tunnel in South East London, but tonight we'll be camped on the edge of 190 acres of fields that regularly see red kites wheel overhead, red squirrels nest in the trees and red deer roam the fields.

Glass-fronted and built from sustainable timber, Brockloch Bothy sits up a farm track and through a bluebell wood near the eastern edge of Galloway Forest Park. Insulated with sheep's wool, heated with a woodburner and fitted with a four-hob gas stove for cooking, it gives you all the modern necessities – a hot shower, a double bed, a sofa and a solar-powered socket for your phone – as well as plunging you feet first into the Scottish countryside. Drive back down the farm track and you're a few miles from the largest forest in the UK. Take a short walk in any direction from the bothy, meanwhile, and you'll soon bump into some of the local fauna.

We're here to do just that: escape the clutches of London for somewhere rugged, wild and completely unlike the capital, and use as little of our dwindling holiday allowance as possible while doing it. Immersion is immediate: as we walk down the lane towards the 300m hill a mile or so in the distance, dozens of juvenile pheasants take flight from the undergrowth – their small, awkward wings making a sound like the struggling rotors on a clapped-out old helicopter. We duck and cover our eyes as they float awkwardly over our heads and across the hedgerow into a nearby field. Continuing down the lane, we forage from a blackberry bush here, spy a bounding hare there, watch buzzards circle high above a quarry and – just before turning off at a row of holiday cottages – two young red deer peer unblinkingly from woodland on the other side of a moss-coated wall. By the time we've reached for our cameras, they've bounded deep into the woods.

Unloading at Brockloch Bothy, Galloway, Scotland

valleys undulate, outcropped hills ripple in the distance and trees dot the landscape, growing thicker and thicker

Known affectionately by the locals as 'the highlands of the lowlands', this land takes on an epic feel given its relatively small scale. Valleys undulate, outcropped hills ripple in the distance and coniferous trees dot the landscape, growing thicker and thicker the closer you get to the forest park. From the cottages, we stroll up the hill as the sun battles the incoming drizzle, trying to get a vantage point on the surrounding hills and forest from on high. By London standards, this is pretty epic. By Scottish standards, the sight of a local crofter wandering quietly past us in the rain wearing a threadbare bucket hat, jeans and a heavy flannel shirt tells you all you need to know. But we're not here just to see the landscapes and soak up the wildlife – we're here to see what this place looks like when it gets dark.

Why? Because a decade ago in November 2009, Galloway Forest Park was designated the first Dark Sky Park in the UK – and just the fourth in the world. Out in these woods come nightfall, it's not just a little bit dark, it's darker than anywhere else in the UK and Ireland. Thanks to its elevation, low population and geographic location, the northeast corner of Galloway Forest Park is the perfect place for stargazing, and has been home to the Scottish Dark Sky Observatory since 2012. Looking out across the park from a 280m-high hill, the observatory takes advantage of the 300 square miles of light-pollution-free landscape, giving out towards Jupiter, Saturn and the vast swathe of the Milky Way. Even the 4,000-person-strong town of Newton Stewart – some 20 miles away on the opposite corner of the park – has had its lampposts refitted to glow less brightly and send their light downwards to increase the area's potential for stargazing.

We get back in the car as dusk draws in, the light weighing in red, yellow then blue across the valley, setting the hills and lochs ablaze to our right. Before long, we're travelling in total darkness, and the drive to the observatory takes on a quest-like quality: flipping through the directions on a stapled-together printout, we follow a Rubik's cube-like set of permutations that guide you from the village of Dalmellington right up to the observatory's front door.

We cross an old stone bridge, drive for a mile until we hear the car rattle over a cattle grid, take a right turn at a crossroads after another half-mile and head down a single-lane track into the woods. After a quarter of a mile, we open a gate and drive across a narrow, sideless wooden bridge before winding up hairpins through two further gates.

Suddenly, the observatory's white dome shuffles into view at the top of the hill, and having seen no one for more than an hour in the car, we're suddenly surrounded by a hive of activity: families hop out of hatchbacks to head inside, young couples pull on their coats and hats for a few hours in the night air and voices echo excitedly out over the valley. Inside, the building is small and simple: a single-room museum, a planetarium for lectures and demonstrations, and a small shop that – among souvenirs and stationary – sells bars of Galaxy, Mars and Milky Way. Someone here has a good sense of humour.

Hiking in Galloway Forest Park, Scotland
Dark skies within Galloway Forest Park, Scotland

Resident astronomer David Warrington guides us into the planetarium to demonstrate the differing levels of light pollution experienced in cities, suburban spaces and countryside on the screen above our heads, then shows us some of the sights that have been seen from the observatory since it opened in 2012.

Not just limited to stars and galaxies, the observatory has also seen noctilucent clouds of shimmering ice crystals and – on the odd occasion in winter – the Northern Lights. After ten minutes of cooing at projections on the panoramic domed ceiling, we're up on the rooftop observation dome for the real deal: squinting into space through the observatory's half-metre-lens mirror telescope.

As a veil of thin cloud whips across the furry night sky it takes David a minute or so to move the dome and focus in on different stars before calling the group to look at them. We take it in turns to gaze through the viewfinder, each of us greeted with the prismatic glow of a star twinkling in front of a backdrop of black so dark and depthless that it plays tricks on your mind. Hanging almost eerily in the foreground, it's like looking at a distant, astral Punch and Judy show where stars sit in front of a curtain that blows all sense of distance, depth and perspective.

But actually looking through the scope is only a tiny part of the experience: out on deck in the right conditions you're treated to an absolute light show. We put our phones away, turn our backs on the glow of Glasgow that bleeds over the hills to the north from some 50 miles away and after five minutes or more in the darkness, our eyes begin to adjust to the expanse above. We start by picking faint wisps of cloud out of the darkness and then rest on more and more glittering stars in the sky beyond. Some are immediately obvious, others are minuscule and barely visible, but the longer I look, the more that floods into my retina. After about 20 minutes of looking, chatting, pointing and waiting, enough cloud moves to unsheath an entire belt of stars – more than I've ever seen in the UK – and after that, the grey-cream lick of the Milky Way appears. The process is slow and the shimmer barely visible, but it's there.

The Scottish Dark Sky Observatory

each of us is greeted with the prismatic glow of a star twinkling in front of a backdrop so dark it plays tricks on you

Suddenly, David's voice pierces the silence from inside the dome: "I've got it on Saturn!", he cries, the excitement palpable through the tinny, echoey resonance in his call. We rush inside again, the first few silhouettes walking away from the telescope muttering in hushed excitement: "The rings are so clear," says one, "I feel emotional seeing it so clearly," says another before the third or fourth says he can't see anything through the lens at all. The clouds are back – and for good this time. "This might be one of the best locations to see stars in the UK," says David, "but the UK isn't always the best place for telescopes."

Back at the bothy an hour or more later, I can't sleep. My eyes are heavy, the wind raps lightly at the window and my watch reads 1.45am as I twist my neck to gaze through the skylight above me. Instead of blankets of blackness, I see a compact group of stars through the small rectangle. Getting up, I lift the blinds and look out over the valley beyond the window: the clouds are gone, and the sky is shimmering and full.

Early the next morning, we wind out into the forest park to meet rangers Hugh Gunning and Ben Askew, driving through 18 miles of lanky pines past logging trucks and shapely spruces destined for people's living rooms come Christmas. While the scenery here is big, this isn't wilderness in the frontier sense: with so much privately owned and maintained land, nowhere in the UK is. About 90% of the land here is actively forested, producing as much as 500,000 tons of timber per year. At one time it was thought to be the biggest tree farm in Europe.

But that doesn't make it feel any less wild. The rangers drive us up to the trailhead at Bruce's Stone. Halfway up a mountain on the north side of Loch Trool it offers panoramic views of the water and surrounding valleys, and during late summer acts as a showground for rolling cliffs of vibrant purple heather. The stone itself commemorates Robert the Bruce's first victory over the English in the Scottish War of Independence, while the hillsides around the loch are littered with debris from the RAF flight training that went on above the lake during the Second World War. Add to that the abundance of hikes, runs and climbs in the nearby hills and opportunities to kayak and fish nearby and you've got a place that appeals to almost every kind of outdoors lover.

As we pass the trailhead car park, campers prep tea on stoves, locals harness up their dogs for strolls and serious walkers arrive to start day hikes to the summit of Merrick, southern Scotland's highest hill.

"If we'd bothered to build a big enough cairn up there, we'd probably have a Munro in Galloway," jokes Ben. "That'd definitely bring people here, but do we want that?"

"Part of the charm," Hugh chimes in, "is that parts of this area are like a mini Highlands – you don't have to travel far and you've got a different type of scenery."

He's right: half an hour later, we've come down from the hillside, left the sweeping loch behind and are staring at a young stag and half a dozen does from the confines of a hide at the forest park's Red Deer Range. Home to roughly 60 red deer, this 200-hectare range of fenced-off moorland habitat allows you to see the UK's largest land mammal in its natural environment.

Getting there

Stay at Brockloch Bothy from £300 for two nights. brockloch.co.uk; Tour the Scottish Dark Sky Observatory from £16. scottishdarkskyobservatory.co.uk; For more on holidays to Galloway Forest Park, head to visitscotland.com or dumfries-and-galloway.co.uk

"I didn't realise until I went up to Skye for my honeymoon and noticed the similarities in the landscape, but there's a lot to be said for this part of the country," says Ben, who's lived his whole life between a campsite in the forest park and the town of Newton Stewart.

"A lot of people get in the car and head for the Highlands," he says. "I totally understand why – it's beautiful, it's famous and it's the Scotland you see on biscuit tins. But not many come up the motorway and turn left."

And they should: this is a place that boasts some of the most majestic wildlife in the British Isles, and some of the most varied and accessible wild landscapes, too. Six hours up the motorway and a little bit to the left and you're in a world you didn't know existed. I think most wantaway Londoners can spare a Friday's holiday for that.