If you are feeling like supermum then use the Deceptively delicious book by Jessica Seinfeld. I just made her blueberry oatmeal bars with spinach puree and they are really yum. I cut down on the sugar. She has some really great recipes for snacky stuff in there.
I will just reel off what I give: all types of fruit, often a selection, raisons, mini cheddars, crackers and cheese, peanut butter on bread, mini toasts with philly cheese, cucumber, mini hobnobs (occasionally as they LOVE these), popcorn (mine are a bit older than yours), soft fruit bars, honey bread, cheese sticks, cocktail sausages ... that's all I can think of for now!