Haylstones, where you are staying is very close to Heads of Ayr fun park, its absolutely brilliant for kids your ages. Its next door to the Ayr Haven caravan park, although its got nothing to do with the caravan park. The road outside is the Dunure road, its just outside the village of Alloway, which is very famous for all things Robert Burns. The haeds od Ayr park has lots of trampolines, large bouncy pillows perfect for liitle kids, slides, horses to feed, a very small zoo-ish area, picnid area, great sand pit fun area and lots of tame animals ro see or feed. It really is great outside fun, a family ticket costs £30, includes 3 kids and 2 adults, the in door restaurant isn't too expensive or bring your own picnic, loads of nice benches. Can you tell we love this as a day out??!!
Also near you is Kelburn country park, right just outside Largs. Again a great day out, great swings area, fun maze, nice countryside, picnic area, ducks, bird centre, lovely castle to visit, again a great day out.
Also Culzean Castle, part of the National Trust - lovely swing park, great lakeside walks, small walk down to the beach, lovely gardens for littles to run round.
Hope this helps!