Soup - make a big pot and have it for lunch for several days. Faves here are lentil/cauliflower/squash. To stave of boredom eat with different toppings e.g. crumbled feta, herbs, sprinkle of seeds, chilli flakes, parmesan, croutons, kale crisps.
Frozen fish fillets (get whatever is cheap) baked in foil with a bit of oil and lemon/lime juice, garlic, chilli flakes, serve with green veg, maybe noodles or rice too.
Daal - I do a large portion of Madhur Jaffrey's basic recipe which is really delicious and super cheap. Eat that for dinner a couple of days a week with a tomato and onion salad, a bit of yoghurt or some naan. Maybe not the same day as the lentil soup 🤣
Omelette with tons of herbs and a bit of parmesan.
Fritatta, again can make a large one and portion it out, great with leftover veggies, you can add ham/bacon if you have it, potato, peas from the freezer. Serve with a salad.
Beans on toast!