For main meals, I tend to use variations on dehydrated pasta in sauce and a couple of peperamis chopped into it. if you can afford it, the specialist camping stuff you add hot water to and eat from the pouch is the least faff, although Batchelors is a lot cheaper.
for during the day, I tend to carry flapjack, mixed nuts, maybe a pork pie or scotch egg. instant porridge or meusli works well for breakfast – I just add a portion in a sandwich bag with some dried milk, coconut and mixed seeds, then add water in the morning.
The main thing is to have stuff he can cook with minimum faff, and minimum cleaning up. If he rolls into camp tired and wet, you don’t want him to have to summon up huge reserves of self-discipline to put some food into himself.