Just checked online and Asda do a whole chicken from £2, I'd get that and maybe some oil/ fat of some kind to roast it.
They also do a bag of frozen mixed veg for £1. I'd get that, some cheap spuds and maybe gravy granules (again asda value range - 25p) have 2 - 3 meals from that.
Any pickings left of chicken can make soup with some of the veg in, could make stock from the bones if she was so inclined, add some pasta to bulk it out.
Basic/value pasta or noodles, bread, tinned tomatoes, baked beans, eggs, block of cheddar. Tinned tuna. - could give omelette, eggs on toast, tomatoes on toast, beans on toast, pasta with a tomato sauce - could add some cheese, any leftover chicken or tuna, some veg, tuna pasta bake, pasta + tuna salad (with the frozen veg cooked and cooled or fresh if you manage to fit it in budget). As a student I loved instant noodles with tinned sweet corn stirred in - asda do 25p chicken flavour noodles.
Wonky veg box def if they have it. They're doing a 1.5 kilo of apples for £2. Or any reduced/cheap fruit could be stewed and eaten for pudding (I love stewed fruit so maybe that's weird!) or stirred into
Agree milk and porridge oats seem to be the way to go for breakfasts. Asda have a bag of porridge for 75p.