Mine like taking hot food in a vacuum flask - pasta or filled ravioli and sauce, curry mixed with rice, soup with mini pasta shells added.
Sausage and bean casserole mixed with rice or pasta (I cut the sausages into bite sized pieces so easy to eat with just a fork).
On other days I send a sandwich (two slices of bread, filled with ham or cheese, pate, or marmite). Peanut butter not allowed, otherwise they'd choose that.
Either a piece of cheese, a hard boiled egg, or half a mini pork pie, a mini scotch egg or bit of quiche or similar- they might have this at break time or as part of their lunch.
Veg - chopped carrot or celery sticks with dip (hummus or cream cheese, I find other dips are too runny).
Fruit - usually apple, banana or satsuma - this might be eaten at break time.
Something sweet - either a bought bar like a club or a penguin or cereal bar, or a homemade cookie or flapjack or similar.