Use Too Good To Go app and find supermarkets that are offering bags for a few £ and buy one. Remember much of what is in the bag needs using on the day, so google recipes and freeze anything you can't eat.
Ramen noddles with frozen vegetables is really nourishing esp if you add an egg or chopped cold cuts.
If you've any bananas and rasins/nuts, make some no added sugar banana bread for dessert or make some biscuits - I'm assuming you have some staples - sugar flour and oil to do this.
Cereal is a really nice supper treat.
Cheesy beans on toast for tea.
Jacket potatoes with bolognaise filling or even pasta with bolognaise can be cheap - pasta is less than 40p in aldi, white rice is 53p. Buy pork and beef mince - it's a big packet and less than a £5 per kg, so 2 or 3 meals if you bulk it up with frozen veg which is £1.
Have a look at the cost per kilo of a joint. I think spatcock chicken was less than £4 per kg - that's poss 4 meals if you add inexpensive veg, a sauce and potatoe, noodles, pasta or rice.
Or go vegan. I recently made a cauliflower curry, it was so filling and cost less than £1.50. There was loads of it too.
Sandwiches for lunch, or soup with a slice or two of bread.
Good luck xxx