Then you would be very, very wrong. Durdle Door is very much dark enough to see the full expanse of the Milky Way. As are the North York Moors, the Shetlands, the Orkneys, the Scilly Isles (much of Cornwall in fact), Bodmin Moor, Snowdonia, the Cairngorms, Exmoor, Dartmoor, the Brecon Beacons, the Lake District (which has a dark sky festival every year), the Peak District, the South Downs

There are, in fact, several Dark Sky festivals around the UK annually

• Cumbria (Lake District, 28th October - 12th November this year)
• South Downs (4th - 17th February (the South Downs National Park was designated an International Dark Sky Place (of which there are only 20) in 2016)
• Yorkshire Dales and North York Moors (10th - 26th February 2023)
• Wales Dark Sky Week (17th - 26th February in the Brecon Beacons, Snowdonia and Pembrokeshire Coast National Parks)
• Northumberland Dark Skies Festival (TBC) - the first designated International Dark Sky Place in England.
• Exmoor (every October)

https://www.darkskiesnationalparks.org.uk

The UK has two International Dark Sky National Parks (Northumberland National Park and the Elan Valley National Park in Powys, mid-Wales).

We also have four International Dark Sky Reserves (Brecon Beacons National Park, South Wales, Exmoor National Park, Devon, Moore's Reserve, South Downs, and Snowdonia National Park in North Wales).

Additionally Coll, in the Inner Hebrides in Scotland, Moffatt, Dumfries & Galloway, and Sark in the Channel Islands are designated International Dark Sky Communities.

https://en.wikipedia.org/wiki/International_Dark-Sky_Association