I meal plan and buy what is needed on the list only.
I double up on cooking, shep pie, bolognaise, curries etc, freeze half. That then makes "free" meals the following week.
Buy only stuff on offer, do ALLOT of freezing.
Dont buy many goodies, buy a multipack of crisps, on offer every now and again, once they are gone, they are gone.
Packed lunches every day for school & work.
Only get washing powders etc from B&ms or homecare shops, much cheeper than supermarkets.
make my own cakes.
Fruit and veg from aldi/lidle, fraction of the cost at supermarkets.
We eat very very little meat as well. Meat is just too expensive. I do buy very good quality mince though. Dont mind paying a bit extra for that, but it does make 6 meals.
Use my slow cooker ALLOT, buy chicken thighs/drummers, very very cheep and cook them in slow cooker, they drop to bits and i can make curries out of them.
All sorts of tricks up my sleeve.
Martin Lewis is my guru, i studied his website and got loads of ideas from there.