The key is using whole foods so there's no waste, that keeps cost down. We're veggie as well which means it's easier to make cheap meals. On Sunday we'll have a roast, then the broccoli stalks will become soup for another night (if I don't have enough I top up with frozen which is fine for soup but not nice as a vegetable on your plate) or they get finely chopped with carrots, peas, onions, garlic, ginger, chili and soy to make egg fried rice.
Fry garlic, add chili, add bag of fresh spinach, once it's wilted add cooked spaghetti. Stir, serve with Parmesan
Cook pasta. Fry garlic, add block of cream cheese, stir, add little pasta water to loosen. Add Parmesan. Add pasta. Stir, serve
Lots of stews can be done in the slow cooker
Jacket potato with beans/ cheese/ coleslaw
Curries freeze really well so are brilliant for batch cooking
If you're trying to make the change to eating less processed food then make cake and biscuits too. Any big change in diet can make you feel your missing out, having something delicious to enjoy will stop you nipping out the the shop for a slab of Cadbury's. We usually have chocolate cake and oat and raisin cookies