There is a big sandpit behind the cafe, but I think it was only put in last year? I don't remember it before then, but then I usually go with a packed lunch so don't usually go in there. The original sandpit is off to the right, near the big wooden fort, next to where the big kid climby, swingy things are.
Cafe - follow the left path from the car park until you get to the gift shop, the cafe is a white cottagey building with pub style benches and tables outside, its to the left and behind the gift shop. Does that make any sense?