Walk rather than use the car where you can, saves wear and tear, fuel and parking costs.
Don't go shopping. I find if I walk into a shop for "just one thing" I'll nearly always come out with a few other things on top, so that £1 pint of milk becomes a £5-6 of stuff we didn't need. I now try to do without whatever we've run out of, rather than just nip out to replace it.
Move your shopping to lidl or aldi - I switched from waitrose earlier this year and honestly I've cut my grocery bill in half. Some of that is to do with limited range, so fewer treaty nibbles, but the rest is just sheer bargains (£38 yesterday in aldi for a full truly; virtually identical shop in sainsburys 3 weeks ago was £69).
Check your direct debits - are you paying out for warranties on dead items, or sponsoring charities you'd forgotten about, anything like that?
Don't eat meat every meal, and when you do, go for cheaper cuts and bulk it out with other stuff.
Eat what's in season - youve probably missed the blackberries but see if there are any unadopted apple trees all forlorn and lost (we have some which have grown from discarded apple cores in a local park); we've found chestnut trees too.
Make as much use of your freezer as you can, and check when local shops discount stuff. Our local coop reduces meat joints at around 3pm on a Sunday, once it's too late to cook them for lunch. But that's half price for the week after if you go at the right time.