General tips
Meal plan, but be flexible to incorporate special offers
Have a supply of staples in the cupboard to make meals with, eg tin tomatoes, coconut milk, curry paste etc
Shop at Aldi/Lidl for the most part, go late afternoon/Sunday pm to the main supermarkets for bargains
Get to know prices on MySupermarket; set up alerts for special offers for things you buy regularly
Account for everything you throw in the compost caddy (that’s not teabags/peelings/egg shells etc). Write a list with an estimated cost… get a feel for what you’re throwing away and adjust future shopping accordingly. British families are typically throwing out £700 worth of food per year. The micro-chore of writing it down will act as a disincentive to buying excess.
Don’t go shopping when you’re hungry
Downshift a brand level on everything till you notice a difference… quite often the only difference is the graphic design on the packaging and the advertising… is it worth paying a premium for this?
Buy a big sack of potatoes, keep them dry, away from plastic and in 100% darkness and they should keep for months. Many times cheaper than buying £2 plastic tray of 4 baking potatoes.
Have a couple of uber cheap meals per week… eg lentil dhal, chick pea & veg curry, chicken livers etc
Instead of pizza, buy a garlic flatbread, add a smear of tomato puree, a sliced ball of value mozzarella (43p) and your choice of toppings like salami, mushrooms, olives etc. Only a few moments more and you’ve saved a few quid.
Don’t buy individual yoghurts, buy big tubs like the 1 kg ones in Lidl and decant into a small pot to serve
Next summer try growing things like cherry tomatoes in hanging baskets and courgettes on the patio
Grow cut-and-come-again salad leaves on the windowsill/balcony instead of buying salad leaves which are the most thrown away food items.
If you roast a chicken or chicken thighs, save the bones, boil with a small carrot, celery stick, half onion, 5 peppercorns. Slow cook for 2 or 3 hrs, use as a base for soups and risotto.
Leftover crusty bread? dry in a oven that’s cooling down from something else, make breadcrumbs or croutons. Or make bread and butter pudding.
Top up shops
Don’t!
Just take enough cash for what you immediately need.
Go to a main supermarket on Sun pm and get a couple of 10p loaves, stick them in the freezer.
Buy a couple of cartons of emergency UHT milk, it’s only 49p/litre in Aldi. It’s nice enough in tea and on cereal to see you through a couple of days.
Keep basics in the cupboard for simple meals eg pasta & sauce, baking pots & beans, tinned sardines and rice
Snacks
Don’t buy them unless it’s a one off treat.
Make your own… buy popping corn kernels, oats/butter/sugar for flapjacks, banana bread with freckly bananas, HM oatcakes etc
Buy very simple cheap snacks eg rich tea or digestive biscuits, or have frozen bread for toast and peanut butter on hand.
Drinks
Just have tea, coffee, milk and water in the house to drink.
Maybe cheap squash diluted to gnat’s pee strength for kids if they’re fussy buggers like I was 
One bottle of wine/70 cl of nice cider/ale to share between 2 over the weekend, can of pop for kids
Cleaning
Have a supply of rags like old t shirts for cleaning up spills
Kitchen roll kept just for pet/kid accidents, red wine spills and draining fried food
Toilet paper… just tear off 2 or 3 sheets per wipe, the whole full on hand mummification thing is like flushing £5 notes (and trees) down the loo!
Just use the basics… a general purpose spray, washing up liquid, loo cleaner, microfibre cloths are all you need. Things like passion fruit aerosol bath foam cleaner are wasteful guff.
Vinegar and bicarb are strong and effective cleaners, yet are pennies and earth friendly. Vinegar is the most effective window cleaner… fill an empty spray bottle 1/3 vinegar, 2/3 water. Apply to windows, wipe with scrunched newspaper then buff with a chamois or microfibre cloth. Also great as a general purpose spray.
Dishwasher tablets can be cut in half (wipe very oily baking trays etc with a waste paper napkin or newspaper)
Cut back on laundry powder 10 ml at a time till you notice a difference. Most people, following the directions, are using far too much. Pre-treat specific stains, rather than chucking scoops of powder into the main wash & hoping for the best.
Cut out fabric conditioner, just use white vinegar and a few drops of lavender oil in place if you feel you need it. The vinegar smell dissipates as it dries, you don’t smell like a chip shop 
Tumble dryer sheets are a bonkers gimmick not needed