Nothing beats bread as a basis for lunch.
If buying for one choose small loaves or two or three brown, wholemeal, granary or white rolls to add variety. Use the same basis as for main meals, starch foods, vegetables and fruits and a bit of protein eg meat, fish, cheese etc to go with your bread. Soup for lunch is a good way of including vegetables whether you make your own or buy tinned soup and add vegetables, beans or pasta to it. Use salad from the previous day eg coleslaw, a mixed simple salad of chopped tomatoes or grated carrot to add to a roll for a packed lunch Many of the light meals ideas can be used as a main meal. You could also use any leftovers from the evening meal that will carry eg a piece of pizza or quiche.