There are things you can do which may not affect your lifestyle too much - I looked into shopping at aldi but it doesn't work for me as its far away and I work and just don't have the time:
a) Double check every penny you spend - eg I shop at tesco but buy value cottage cheese, chopped tomatoes, big pots of yoghurt, eggs (rather than small kids ones), only buy luxuries like berries / crisps / chocolate / snacks / granola bars / ice cream if on offer, and impress on the DC that its a treat and when its gone its gone. My kids take a couple of cream crackers to school as a snack. I use the points for days out - so whereever possible avoid paying entrance prices for days out.
Stop buying expensive kids products - and only dish up to your kids what they will eat, you can always give seconds; and if they don't want seconds you can have it for dinner or they can have it the next day. Never cook fresh food if there is still left-overs.
Never ever buy snacks when out and about, always more expensive. If you are working take packed lunch.
Always see if you can manage with the cheaper option - eg my DD can use tesco or boots cheap on brand hair conditioner and not feel deprived rather than l'oreal hair conditioner for kids etc. Same with handsoap (apart from maybe downstairs loo where guests see) and shower gel.
Also I go to asda roughly every 2-3 months to stock up on cupboard stuff thats cheaper there and kids clothes.
b) Boots is expensive - I hardly shop there - most stuff they want you to buy isn't actually needed, although often good three for twos. Actually doesn't matter if card is in H's name, you can still spend the points. Look out for little things that save money eg can use calpol 6+ but half the dose instead of baby calpol if your kids are aged 3-6.
c) Mooncup and never buy sanitary products again. Eplitator and never spend any money on hair removal again. Try and space haircuts out more, dye your own hair, cut DS's hair with clippers.
d) Recycle around half of the birthday presents your DC get, and buy any others needed in the sales. Look out for cheap wrapping paper and never bother with cards.
e) Stop using kitchen / bathroom wipes - and look out for cheaper cleaning products.