£60 ish a week for a family of 4, (2 adults, 2 preteens).
One child has packed lunch, one school dinner. Children fed one night per week at grandparents.
It's on the cheap side, but we eat well. I stock up on reductions when I see them, and I don't tend to buy many branded products, expensive snacks or convenience food. We eat typical meals - lasagne, shep pie, spag bol, fish pie, pork chops, paprika chicken, enchiladas, jacket pot, omelettes, pasta bakes, roasts etc, with loads of veg/salad. Always have a full fruit bowl.
I do buy value toilet roll, bin bags, wrapping foil etc. I buy own brand cleaning products (except washing powder, when I tend to buy whatever brand is on offer.)
We're not awfully short of money, I think I'm just naturally tight!
I can't imagine what I'd spend £100+ a week on in the supermarket. I don't go to one that sell clothes/homeware though, so perhaps that's why!