If you prepare the yoghurt / cottage cheese with fruit it in the morning in a container that keeps the temp low and bring a small bag of assorted nuts, it's easy to carry around. It's got all the necessary calories (proteins, some fats and some carbs).

And why are wraps out? If you keep them light and stuff them with stuff that does not leak (cheese, ham, maybe pepper strips), you can pack them in a tin foil wrap and it'll be perfect.

Many leftover dishes from the night before might also work. You might have to eat it cold, but there are many things that are not all that bad when it's cold.