Eggs, cheese, pasta, potatoes, onions as basics.
Bacon lardons (Lidl do a double pack that is good) for some meat.
Baked potatoes with baked beans.
Frittata/Spanish omelette things with cheese, onion, whatever veg on hand (pepper, frozen peas, mushrooms etc), diced potatoes and some meat if you have it - bacon bits or bits of Cooked chicken are good. Or veggie version.
Mac n cheese, if you get mushrooms and bacon bits it works well (I also add onion, garlic, peppers, courgette and frozen peas). Make a large batch, freeze leftovers and reheat that as pasta bake during 2nd week.
Nasi Goreng. Leftover cold cooked rice stir fry dish. Using the oil from a tin of tuna (or regular cooking oil), fry diced onion, garlic, whatever veg you have (mushrooms, peppers, small florets of broccoli or cauliflower l, sliced carrots, frozen peas etc), sweet corn from a tin, the tuna, couple tablespoons mild curry powder and your cold rice. Can add leftover cooked chicken or cooked prawns/white fish if you have any. A great dish to use up ends of things.
Elastic chicken - making 1 chicken last a few meals by roasting, using leftovers in reheated in gravy or smaller amounts adding to risotto, nasi goreng, pasta dishes, sandwiches, HM soup etc.