I bought lunch boxes with three compartments.
Big compartment is for carb/protein.
One small compartment for veg.
One small compartment for fruit and occasional sweet item.
THe whole box goes into a bag with a strap and a pocket for a water bottle.
Carb/Protein:
Sandwiches - bread, pitta, wrap
Fillings - ham, cheese, houmous, smoked mackeral pate, smoked salmon if I am feeling generous, cream cheese, marmite.
Sometimes slice of quiche or a savoury muffin.
Sometimes I put cheese and tomato into the wrap, dry toast it in a pan and call it cold pizza.
Sometimes I put in rice cakes or crisp breads and leave the fillings in chunks for them assemble themselves.
Veg: two or three of the following -
Slices of cucumber, peppers of all colours, a couple of cherry tomatos, carrot sticks, raw fresh peas for DD1.
Once in a while I put in a small jam jar of houmous for dipping.
Fruit:
Grapes, a halved kixi (cut side down) with spoon in the lower compartment, rarely a handful of mixed dried fruit, blueberries, in season soft fruit. Apples, pears, bananas and tangerines have to go on the lunch bag as they don't fit in the box.
Occasional sweet - perhaps once a week:
A biscuit or a choc coin - cake or muffin if I happen to have baked.