Pasta, feta cheese (one packet divided into 5 portions), sprinkling from a tub of dried herbs (about £1 ish, lasts forever), pepper and oil.
Family pack of cheddar, tomatoes and pickle, bread. You can manage without butter if you toast the bread and melt the cheese after you've made the sandwich by putting it in the microwave for 40secs.
Can of soup into a bowl, half a tin of veg thrown in, microwave and add a couple slices toast to dip in.
Porridge with banana.
Toast and jam.
Bran flakes are more filling than other flaked cereal and cheap if you buy unbranded, add sugar and milk. You'll use less milk if you have it warm, microwave half cup for 1min then pour over the bran flakes.
Microwave jacket potato with butter and beans or tuna and cheese. Buy the family packs of cheddar and multipacks of tuna (and use half tin per potato, it keeps refrigerated until next day) to keep it affordable.
Rice, teaspoon of mixed spice (packets from the World Foods aisle in the supermarket give better value for money, approx £2-3 and lasts forever) tin of fish (preferably in oil or tomato sauce for flavour), half tin of veg. Cook rice, mix together and warm through on half power in the microwave for a few minutes.
Tin of sardines on toast. Buy the ones in oil and you can manage without butter.
Half tin of tinned fruit with cheapest vanilla ice cream for a treat.
Plain rice mixed with a desert spoon of jam and a couple teaspoons sugar for a snack/dessert.