@Linkat,
You can see Henge from the road, but only in the distance. The original road that went past it has been diverted. Now you have to drive to a ‘heritage area’ where you can catch a shuttle, or walk, to Henge but only after you’ve paid an entry fee.
If you’re doing Arthur then Tintagel and Glastonbury are very important if you follow the southern claim that puts Camelot in the vicinity of Glastonbury. The northern claim has it in Carlisle.
There’s all sorts of other minor Arthur sites like Cadbury castle in Somerset. I’ve got a big coffee table book called Lore of the Land which looks at folk tales county by county. There are some duplicates, but most stories are fairly original.
Cornwall probably has the most. I remember watching a documentary about a band who were staying at a cottage on the moors. The pub was about a mile away,and on the way they passed a rock formation where the Devil would watch gladiatorial style combats by demons eager to gain his favour. Now on the way there in the light they could laugh and joke about it. The return journey in the dark after a few beers wasn’t quite as jovial.