I think we need to decide whether we are talking about a 'normal weekly shop' for food that is to provide for most meals for packed lunches, or something else entirely, as Manatee's example appears to be:
Even if you say 10 pw for cleaning products, which would be a lot for a couple and another tenner for cat food (how many cats do you have - we get the little 20 p trays from Aldi - 28 of these for 2 cats plus some biscuits is probably about 8), that would be about 100 pw for food and wine, that is just breakfast and some evening meals?????
Even if you are living on smoked salmon breakfasts and M&S ready meals, there must be a substantial amount of wine in that amount, so not food really??
I don't think it's reasonable to cite a 150 pw shop that includes booze and luxury food as evidence that rich politicians are out of touch (they are, but that's another issue), or that it's not possible to feed a family on lesser amounts.
FWIW, DP and I both work full time and shopping for us including 2-3 cats, mostly from Aldi, but with meat from a naice farm shop, probably costs about 200 - 250 pm, so a family with 2 young DCs could easily do it for quite a lot less than double this amount, particularly as DP is a greedy fucker that eats a lot.