How about Paultons Park (for the 7yr old) and Peppa Pig World (for the 3yr although i am sure the 7 would still enjoy) In Dorset near Bournemouth, great position for exploring the south coast and then stay at some where like BournemouthCottage which is reasonably priced and means you could explore The Jurassic coastline as well?
We spent Easter near by last year, hired a cottage for a week about 5 mins drive from there. This place was great because it has outdoor and indoor activities so plenty to do on rainy days and the area has beaches close enough on sunny days. And it was really cheap! http://www.woodlandspark.com/ I wouldn't actually mind going back there but part of me is thinking there ought to be similar places somewhere else in the UK with beautiful places to stay and visit. I have 3 and 7 year olds. Both very active :-D I would prefer a cottage accommodation due to the fact that they are usually better equipped with washing machines and tumble dryers. But don't need anything fancy. Please please give me some ideas as where to go. There seems to be so much within UK it is impossible to chose! We are in London and the travel distance would be under 6 hours as dont want to waste a whole day travelling. Please give me some pointers. Thank you!