We spend about £40-£45 a week for 2 adults and one small cat hehe We used to spend up to £60-£70 when we didn't have a car and only shopped at Waitrose.
I make a lot of our meals from scratch using store brand value stuff- ie. lovely homemade tomato sauce made with tesco value plum tomatoes! I buy store brand or value products for most paper goods and other stuff that we've tested out and feel don't dimish the quality and we basically decided what we can stand not being brand named. Instead of buying chicken breasts, we'll buy a chicken to roast and that lasts us for at least 2 meals, often 3. We've just started going to a local Sunday Market where we buy our veggies and fruit for an obscenely cheap amount. As a result, we have been eating lots more fruit and veg and find that it is very filling! All of the veggies are really big, too. For example, We'll buy 4 Aubergines for £2, 2 bunches of Bananas for £2, 3 cucumbers for £1, 6 mangos for £2 (ohh, that was heavenly), 4 Swedes for £1, 5 boxes of strawbrries for £2, 4 honeydew melons for £2. Which means we have had some nice fruit for breakfast or snacks, too!
We realised too that the bulk of our money was being spent on food. So we've decided what we want to skimp on and what we don't. The only things we really don't skimp on are tissues, toilet roll, nice pasta, juice, tuna and Sweetcorn from Waitrose when we can stock up. Also, the cat is finicky- only likes Go Cat brand- thankfully it is cheap! hehe