I would start by buying some silver foil trays with lids (much cheaper on line than from a supermarket). Then you can batch cook. You can also use old takeaway containers if you collect those.
I make large quantities of the following, them freeze them in containers (or freezer bags) with enough for the 2 of us:
Tomato sauce (tinned toms, onions, garlic, any herbs you have, salt, sugar, spot of vinegar). Cooked veg first then add the rest and cook for 30 mins. You can use this as pasta sauce, with meatballs or even liquidise it as soup if you need to.
Spanish chicken. Chicken breasts or thighs, chorizo, onions, garlic, herbs, tin of beans (any sort, not baked beans), tin of tomatoes, olives if you have them. Fry onions, garlic and sliced chorizo. Add chicken chopped into sensible sized pieces. Brown it all. Chuck the tins of tomatoes and beans in a casserole dish with 500ml of stock (hot water and stock cube). Add the fried stuff. Cook in the oven for an hour or so.
Make a bolognese with minced lamb. Use it actually as bolognese with spaghetti or freeze some in your little silver trays to top with mashed potato in the future to make a shepherds pie. Or add chilli and chilli beans to make chilli with rice or jacket potatoes.
Jacket potatoes with cheese and beans or tuna, mayo and sweetcorn.
Make a pizza base (Sainsburys do a good recipe which I will try and find - I've used it for years). Put on anything you can find then grated cheese.
Chorizo is great because you can fry the tiniest bit and it adds a lot of flavour to an omelette or soup.
Buy ready made pastry bases then make quiche. Throw in anything you like then add 2 beaten eggs with a spot of milk then bake.