Trellyn Woodland, Abercastle, Pembrokeshire
The site has its own yurts and tipis, set amongst woodland in a quiet corner of Britain's only coastal national park and just a minute's walk from the sea, so there are only a few pitches for tents. You'll need to book in advance. You're within easy reach of the Pembrokeshire Coast Path and various great bathing and surf beaches, and there are even a couple of decent pubs within a short drive - but you'll probably prefer just to chill out by the campfire in the evenings.
Local highlight: check out nearby St Davids, Britain's smallest city.