How much is a normal amount to spend on food per week?

Depends on where you live in the UK, if you can batch bake, if you have a large freezer, if you live alone, et cetera.

If I had to live on £30 ($40) per week I could & have done in the past. Life on a 30 quid food spend weekly was, to be brutally frank, fucking miserable. It does vary but I'd guess I spend £50 ($64) weekly. I buy locally, little & often & I eat like a King.

With two adults and the occasional guest somewhere between 80 to 100 a week.

I think I'd find it hard to live on £30 a week these days, even though I can happily go without meat, which is currently the most expensive single category of food in our weekly shop (my wife's a dedicated carnivore). Ready-meals are also ridiculously expensive if you look at how much the ingredients actually cost.

We (two adults and a child) cook everything from scratch as a rule, and have a pretty varied diet. We're fortunate that we don't have to count the pennies, so we just get what strikes our fancy when we shop, and I suppose we spend an average of £110 a week.

I live with my girlfriend and we shop once a week. We usually spend 60-80 Euros (Germany). Probably another 10 Euros for small stuff you buy from the nearest market in the week. But I'd say about 80 Euros for everything. Including more expensive stuff such as octopus, salmon, tuna, caviar, Italian and French salami...
Twice a month we touch about 100 Euros, cause I buy Chivas Regal.

my wife spends as much as she can