Cold pizza or even cold lasagne that can be cut into slices (sounds a bit weird but is delish). Also fritatta with chorizo that can be sliced. Popcorn, rice cakes, cereal bars, flapjack and the like for snacking.
Quiche. Mixed salads in Chinese takeaway containers (one each).containers will be useful on holiday too. I've also put individual portions of cereal in takeaway containers and taken a pint of milk before now.