school hols my mum (she had 5 of us and not a lot of $) used to whip up stuff like:
pocket bread with grated cheese carrot and salami
pocket bread with a mix of cheese tomato sauce and tuna (or used to do cheese on toast w this too)
she'd buy a long french stick and make huge sandwiches with salead/ meat / etc but we used to help and made a stack of yummy food for everyone
leftovers sandwiches - we'd always have a lump of left over roast or corned beef in the fridge
picnics