try these sort of dishes that will last a few days in the fridge that you can go back and forth from when peckish , things like stews, casseroles , pies, pasta dishes , stir fry's, lentil and rice dishs.
look into them sort of dishes, if you want to eat good and for cheap, plus you can have them for 2 to 3 days in a row.
cheapest stewing beef in the super market fridge (great taste and tender when cooked slowly)
chicken filets (usually on offer)
carrots
parsnips
mushrooms
cheap packets of soup and noodles
frozen veg mix
tins of beans and various veges ect
sausages
pasta
ready made family sized trays of lasagne (can be very reasonably priced)
cereal
crackers
flour (when needed)
pearl barley (for stews and soups to make them more filling, not expensive)
cheese
bread
leek (I sometimes get )
celery (I sometimes get)
a bottle of some sort of sauce to add flavor.
garlic ( I love it)
tinned and fresh fish (good healthy option)
cooking herbs and spices as needed but I dont break the bank on them.
my approach to shopping is minimalist and I shop at the cheapest super markets, butchers , veg shops, Asian stores.
I tend to avoid ready made meals to keep my bill down, your talking 70 pounds to eat decently
I'm always working on new recipes and ways to keep my shopping bill low while eating decently for cheap.
try to buy stuff as you need it, because if you go and do a weeks shopping you may be tempted to buy stuff you wouldn't
normally buy.
I also shop in Asian stores and supermarkets for a lot of my stuff like noodles and ingredients for rice dishes as they tend to be very cheap.
avoid junk food you don't really need it.
plan ahead of time what you will eat.
some self control is good to so your not snacking to much outside of meals.
50 a week (tight budget , id say 60 or 70 to be safe)
be careful where you shop also, shop at places you know you will get good value and quality for a good price.