We rarely waste food. If you have a freezer and something is coming up to its sell/use by date freeze it.
We buy artisan bread, slice it and freeze it so we always have fresh bread.
You can freeze semi skimmed milk so no waste there.
If I have veg past it's best, I make soup. Chop and fry an onion or a leek. Add other veg always including a small chopped spud whatever the rest is, salt pepper and a veg or chicken stock cube. 20 mins on med on the stove then blitz it with a blender. Add a bit of cream or cheese, or mascarpone. Yum.
Other veg can be roasted with a bit of olive oil, then make your own wrap with the roast veg plus some grated cheese, a bit of mayo, fab.
We always have tinned white beans, garbanzo and haricot beans, chopped tomatoes, tomatoes puree and cheese in the cupboard/fridge, then you always have a meal.
Buy a slow cooker. They're about 20 quid. Chuck in some chopped onion in olive oil, some chopped veg, a stock cube, can of tomatoes put it on low, and 8 hours later you have a stew. Make dumplings, they take 30 seconds and chuck a couple in the last half hour.
We eat very well but I'd struggle to spend more than 60 quid or so a week for groceries etc and there's 2 adults. In fairness we rarely buy cake, biscuits, crisps etc.