Home made hot chips, not the one's you buy from the supermarket.
I make them for my kids and they love them.
How about some home made dip and biscuits...alot of kids like hummus.
Pinwheels (flakey pastry with salami or ham, cheese rollled, then cut and baked).

A fruit platter always goes down well as well.
lollylegs has given some great suggestions.