I rarely use pre packaged foods for DS1 at school, with the exception of yogurts (when we get the big tubs everyone tends to eat bigger portions, so the small individual tubs suit me better). Usually DS1 will have a sandwich, yogurt, sultanas or watermelon and an apple. He sometimes has pasta salad with tuna instead of the sandwich, and a cookie or cake instead of the sultanas if I have been baking. DS1 occasionally asks for the muesli bars and cheese strings he sees his friends having, but he is quite fussy and happy with the diet he is used to. I'm sure your DD will be the same, kids like what they are used to.