are you in scotland?
i'm sure it's the same up there as it here (from talking to my sister) and they get fruit and milk in their morning break for the first few years of school so no need for a separate snack.
lunchbox wise, DS gets a sandwich, roll or wrap, usually with ham, cheese, tuna or egg, a pot of fruit salad or a single piece of fruit, a yogurt, some tomatoes or carrot/cucumber batons, and a drink, either milk fruit juice or water.
He dioesn;t always eat it all, but I make him eat what's left as we walk home from school.