I don't budget anymore because I find it too depressing.
It's too time consuming to shop around for fresh food all the time but I do save an absolute fortune by shopping around for non perishables. Some examples:
Never ever let the loo roll run out, quality test the own brands, always make sure there is a ton in stock in case I don't go back to that supermarket for months.
Same with what, on the surface seems like a little thing - black bin bags. Actually, we get through loads and good ones are really expensive, so I know which are good quality and which are crap and buy six month's worth at once wherever they are best value. Same with:
DW tablets
W up liquid
Laundry liquid
Kitchen towel
I always shop around for cat food as it's now over 45p a pouch and was recently chuffed that Sainsbury's had 1/3rd, which nobody ever does anymore. Again, bought a ton.
Deodorant OH needs is now £3 each but I stock up so much that I can afford to wait up to six months to see it on discount somewhere and usually get it for £2.
Same with body cream (mine is horrific, £6 a week).
Same with my sensitive shower gel.
I never pay full price for my hair dye, it's always a 2 for.
We freeze cheddar. OH knows what's good value so we get 3-6 blocks at once.
I've ditched the Fairy washing up liquid because whilst I agree no other brand is quite as good, we mostly use it to soak cooking pans before going in the DW, so what's the point.
I can't justify the money for Heinz anymore. We got a fancy tom sauce with balsamic vinegar and find we only use it once in a blue moon now. When I recently had Heinz instead, it tasted vile, it's so so sweet.
So yeah, don't bust a gut with the weekly food shop but taking a lot of time to get good value and bulk buy non perishables is really worthwhile.
I can also never be lured into any one supermarket with promises of return discount vouchers if we spend £80 this week and next; more often than not, those supermarkets cost more than the others anyway.
Do you ALWAYS check your till receipts before driving off? I do. About 1/5th of mine are usually wrong. OH almost paid £6 for two GF beers on Saturday until I pointed out they were £4 with £1 off, not the £1 we both thought they were due to terrible shelf labelling.