Jacket potato with fillings and salad Couscous- add tuna and frozen veg to make a full meal Stir Fry Gnocchi with tomato sauce and cheese Fish fingers and baked beans ( or my daughters favourite - fish finger sandwiches!) Pasta with a mushroom/onion/bacon/philly sauce
Do you have a freezer? I make stuff and freeze it in portions. Its nicer than having the same thing 3 nights in a row, easy to heat something through after work, and means I don't have half used vegetables unused and going off in the fridge. You can freeze most thing,including stuff you buy half or fully prepared -jars of pasta sauce with veg added, slices of pies etc
I tend to cook in two main ways: - fast simple things that can be thrown together in half an hour or less and that are easy to do for one such as: stir fries with rice / noodles, risotto, pasta dishes, 'meal' type salads, omelette, chicken breast done on the griddle pan, grilled fish, etc - A large pot of something that can be eaten over more than one day e.g. chilli, soup, curry; or something that can be made into portions and frozen (in individual foil trays) e.g. lasagne, fish pie.
I found the 30 minute cook by Nigel Slater really good for inspiring recipes - they are all really simple, quick, quite nutritious and enough of a treat to make it feel like you've made an effort for yourself.
Having said that my go to meals for one all revolve around pasta and home made sauces, carbonara, spicy tomato and bacon and spinach mushroom and cream.