Also B&M/Home Bargains are dirt cheap for toiletries and can be cheaper than Poundland. You can get tins and packet foods there as well.
Some of the cheaper meals we do (we do have a good store cupboard and spice cupboard)
Veggie egg fried rice - sometimes add leftover chicken and if you cook the rice in stock it's very tasty
Chickpea, lentil and sweet potato curry with rice
Cottage/ Shepherd's pie bulked out with lentils and veg
Beef or Veggie chili (tins of mixed beans or Asda do a frozen mixed pulses bag)
Roasted chicken thighs (1.1kg for £2 at Asda) - herb and garlic with roasted med veg, curried with rice, or lemon and thyme with salad
Spanish omelette or frittata with salad. Chorizo is reasonably priced (£2 a ring) and goes a long way
Med veg, chorizo and bean stew with cous cous
We can do chili for 4 and cottage pie for 4 with 500g beef bulked out with veg and lentils