How do you feel about fish? It is honestly so easy to cook. Salmon, maybe?
You can cook it in a frying pan or in the oven. If you're not confident about a frying pan, then buy a packet of boneless salmon fillets (Sainsbury's do four for about £6), line a tin with sides with foil (this cuts down on the washing up, and keeps the flavours and moisture in), sprinkle some chilli flakes, a squeeze of lemon (it is much cheaper to buy lemon juice in bottles than fresh lemons, you can buy lime juice in this way too), salt and pepper, and then cover the salmon with the foil. Then pop in the oven for 25 minutes.
You could cook jacket potatoes at the same time (they will need maybe an hour and 15-30 minutes in there though, turn them over half way through), and you could also wrap corn in foil individually, and put them in the oven at the same time as the salmon.
Something else very easy and tasty for salmon, or any fish, is to marinade it before you cook it. A small amount of soy sauce, honey and ginger (the ginger puree that you can buy in a tube in Tesco is brilliant - it is with the fresh fruit and veg, they do chilli, garlic, coriander and lemongrass purees too). Mix the marinade together, put the salmon on top and turn it over a few times. And let it marinade - ten minutes would be fine. And then cook it in foil as above.