We lived in an hotel for a month in between rentals. We bought this travel fridge, which comes with a normal wall plug. It's massive:
https://www.halfords.com/motoring/travel-accessories/coolboxes/halfords-40-litre-mains-and-12v-and-24v-electric-coolbox-195723.html?stockInventory=10&gl=15no8upMQ..gsMQ..&gclid=Cj0KCQjwLFBhDmARIsAItqgt7ppa7kRNtSvbKyTvLNefROTPzXOesiGC0XOSfrlPDVytGDECiGC4aAg93EALwwcB&gclsrc=aw.ds&gbraid=0AAAAADrJx6xAZsh4vk8Us3ioOqmz4oI9
We ate:
Cooked supermarket chicken, salads w dressing
We stored milk, cheese, butter in there - crackers with butter and cheese or pate almost makes a meal, although less so for us fatties
Big yoghurts
Pre-prepared fruit; although if he can buy some tupperware or just cheap ziplocks and a knife, it's cheaper to buy a whole pineapple (the ones without the heads are even more economical), and it's surprisingly filling for a breakfast. Tinned fruit is expensive these days. Pineapple is the most economical DIY in terms of what actually fills you up.
Grated red leicester, cheddar, grated red onion - mix with mayonaise to make a really substantial and filling cheese sarnie just like M&S makes.
Other hotel foods
Dips w pitta bread; taramasalata, hummous etc
Big pots of potato salad and coleslaw - could be paired up with cooked chicken, use the chicken strips like a spoon
You can eat rice pudding cold from the tin, throw in a handful of cheap sultanas and a big squeeze of honey, maybe a sprinkling of demerera sugar and you feel a bit less like you're living on the poverty line.
Boiled eggs can be bought in jars, but they're not very economical; might be cheaper to buy them individually from the chippy.
We bought light bamboo plates and plastic glasses, a travel bottle with w/up liquid, and had a towel dedicated to only balancing drying up on, on the floor, against a wall.
If you're willing to help him, then a sliced up gammon joint and also sausages can be eaten cold w coleslaw etc, although they're gross cold, but at least it's cheap protein.
Iirc Maggi branded noodles can just sit in a bowl of boiled water from the kettle.
He should also see if he can corner someone friendly amongst the hotel waiting staff and ask if the kitchen would be prepared to pop a meal in a microwave for him. Don't ask, don't get.
I'll pop back if and when I think of more.
Edit: a lot of the frozen chicken kebab type things that you get in lots of places - Farm Foods, Lidl, etc are in fact already cooked and just need to be left out to defrost - your friend needs to study the back of the packet and look for 'reheating instructions' rather than 'cooking instructions'
And baked beans can be eaten cold. I imagine on thick white bread with decent fresh butter would be tolerable.