For me (SAHM except for 1 day per week), DH, DS1 (4.6) & DS2 (2.2) & Dcat, both boys have very large appetites for their ages - also currently living with my parents but will discount them for now as this is only temporary!
Spend between £100-£200 per month on all groceries, cleaning stuff, cat food, toiletries, nappies etc.
Save money by mainly shopping for any fresh goods (bakery items, meat & fish, fruit & veg) at around 7/8pm when our Tesco reduces them by 75%+. Eg went last night & got 2 large packs smoked salmon, 2 packs meatballs, 1 pack stewing steak, 3 individual pizzas, 1 pack chicken bits with herb coating, 1 pack river cobbler & 1 pack cod for £10. As you can imagine, savings like this make a huge difference over the course of a month!
I also buy milk, crisps, sugar, potatoes, bread, onions, bananaswhen I can't get them reduced at Farm Foods, as it is very good value for money.
Another thing to do is to see if you can buy any meat/fruit/veg direct from source. So, for example, we got a whole lamb direct from a farmer for £90, which is very good value for money & lovely quality too.
I also notice that other people seem to have lots of different types of things. So, for example, we are staying with my parents now. DSes wanted an ice-cream this afternoon & there was a choice of ice lollies, fab lollies, ice-cream from a tub & choc ices, with 3 different types of sauce. We tend to just have 1 tub of ice-cream & 1 sauce & that's it - and everybody is happy with that, so obviously it's a lot cheaper. The same applies for just having 1 or 2 cheeses, 1 pack of ham, 2 or 3 types of fruit etc. And the irony is that as my DM has so much choice, a large amount of it is out-of-date & will get thrown away anyway, so money has been wasted.