Just that!
for me, dd and dh (gluten free, lactose intolerant and nut allergy!)
it’s about £100 per week but we shop at Waitrose 
ill break it into categories
essential food: £80 (meals, fruit, COFFEE , breakfast etc.)
non essential food: £10 (hot chocolate, baking things, fancy bread)
household stuff: £10 (bin bags, paper bags etc.)
so that’s £400 per month
add smol subscription
(£15 pm)
and trip to zero waste shop (£50ish)
£475 ish per month