It all depends on what kind of camper you are.
there are lots of sites where you more or less camp where you like, in woods or on fields, and the kids run wild in the woods, you can have a campfire et. Places like this would include Forgewood, Welsummer or Blackberry Wood all in Kent or E Sussex. Usually well positioned for days out at National Trust places or not too fat from the sea, they have 'facillities' and Forgewood actually has a restaurant.
Or you can try the more holiday-park ones - Wellington Country Park, or on the N Norfolk coast, Kelling Heath. Kelling has a pool, miles of heatland and woodland, v close to the coast, has a takeaway and restaurant facility. Obviously these places are more expensive.
Or there are sites with children's farms and petting zoos on site, like Palace farm.
Or more traditional 'organised' sites maybe like Norman's Bay, with it's own shingle beach outside Eastbourne, or Waxham sands on the dunes in Norfolk.
Do you want a clubhouse and bar and evening entertainment?
Look at a few sites like CoolCamping, or search Campsite UK by map and then other filters like 'beach' or 'campfire'.
Whether a campfire is allowed is often a kind of the touchstone of the sort of site it is.