Paul you could try either Beverly Park which has a fantastic selection of entertainments for children whether it is dry or wet, or Widened Caravan site which is smaller and has far less amusmants for children. They are both in Paignton.
Beverly park is a large site with indoor/outdoor heated swimming pools, entertainment club house with cabaret, games rooms, etc., etc. It caters for all ages from toddlers up. The only drawback is it is expensive.
Widend has an outdoor heated pool, small bar area with limited children's entertainment, small games room with slot machines and pool table and the normal swings, etc. in the play area. The advantage of this site is it is far cheaper, smaller and more guest friendly. The shower/toilet facilities are spotless and other facilities on site include shop and take away hot foods. There is also a dog walk if you have a pet.
The choice is difficult to recommend as it depends on the number and ages of the children but I think that either one will be enjoyable. Beverly Park has a web site but for Widend you will have to phone Julie for the site brochure.
Good luck in your selection of site and enjoy your holiday.