As an area to look at, i can recommend the north-west Devon coast (Barnstaple area), some absolutely stunning beaches up there such as Saunton Sands and Croyde that are great for kids with shallow sea and no shelves

also got a few attractions including Combe Martin Wildlife and Dinosaur park, Milky Way adventure park, and i'm sure there's an aquarium somewhere as well. Plus the best Fish & Chip shop i've ever been to

@
ravon