I live in Cheltenham and have some friends from the Forest of Dean area.
It's really pretty, and if you like being outdoors, there's plenty to do and see - lots of wildlife, walking trails, cycling tracks etc. as well as (I think!) some places to kayak/canoe.
However, from what I've seen of it, it's a very white, middle class place to live with a few working class areas that the younger generation can't afford to buy/rent their own homes in so have to move away or stay with parents forever. The people seem to be pretty nice, but like a lot of villages, there can be quite a strong outsider feeling in places I went to, where people who've lived there 10 years or more are considered "new", and POC are such a rarity that everyone stares (not because they're all racist, but there's genuinely so few POC around that it's like, OMG what are they doing here).
It's also pretty remote, so you'll have long drives to the nearest town or city for shopping or socialising other than at the local pub, and the roads get pretty bad in winter (and any time there is a lot of rain)!
If you're OK with living in a "white class bubble" and struggling to get to a big shop in bad weather, then it's a really beautiful place to live.