If you are grating cheese, grate the full block and freeze what's left for readymade grated cheese.
If you are peeling veg for something, including potatoes, peel whatever you need for the next day and pop it in the fridge well covered with water.
Have some leftover recipes. If you have a roast chicken on a Sunday, buy a bigger one and use the leftovers for fajitas or something. Or soup if there is only a bit.
B and M, the poundshops, Home bargains etc all sell much cheaper biscuits, cereal bars, snacky stuff. Go in payday, buy enough for the month then separate into a weeks supply and hide the rest. That way you don't end up on week 3 with a pack of rich tea left and no kitkats.
Mealplan utilising leftovers. So make a double batch of bolognese and do 1 week spag bol, 1 week lasagne or turn it into a chilli.
Eggs are a really cheap way to fill everyone up. I do Mexican eggs as a teatime meal. Warm your wraps in a dry frying pan, add scrambled eggs and I usually buy one of those tex mex dip trays. Add whatever sauces they want, roll and serve with rice or chips or wedges. My fussy fuckers love it.
If you have some bits of veg knocking about like a pepper, some cherry tomatoes, a courgette etc wang them in a tray with a red onion and roast. When they are done add a squirt of tomato puree and a ball of mozzarella cheese then melt the cheese. Stir through pasta for a cheap and cheerful roast veg pasta sauce.
Do 1 room a day properly. Do windows 1 week, pull furniture out and do corners and skirts another. My 6 year old dusts my skirting boards for stars for his pocket money. Hoover and mop all way through once a week. Everyone puts their own clothes away and keeps their own rooms tidy. Wipe the fridge out before you go shopping and tidy food cupboard as well. Makes it easier to out everything away.
Also give less fucks. If you eat biege food a few nights a week it doesn't matter, just chuck some fruit at them. If your house isn't pristine it doesn't matter. If you are knackered and want a takeaway it doesn't matter. Just do your best, be productive as much as you can and the rest of the time it really doesn't matter as long as you arent living in squalor.