I pay off my credit card every month and stop buying as much as possible if I notice I have spent over budget. I try to shop a day later every week, mainly online with vouchers, and sometimes live out of the freezer and store cupboard to get spending right down. I buy some things in bulk when they're on offer, like dog food, toilet rolls, and cleaning products.
My daughter introduced me to B and M Bargains, a store that is spreading rapidly around this area, and one has just opened near me. The prices are ridiculously low, and they have lots of things like £1 rhubarb crowns and climbing plants, cheap tins of sweetcorn, half price quilted toilet rolls and suchlike. Turnover is fairly random, so there's always something different in there.
I always have different kinds of flour and yeast in my baking cupboard, and can soon knock up bread, cakes, cheese and onion pies, quiches etc if I have guests. I keep Aldi 70% chocolate in stock, so a chocolate mousse can soon be produced, and cocoa powder and walnuts are always there for a quick batch of brownies or cookies, which the grandchildren like to make.
I find that staying away from local supermarkets saves me money. No surprise there. Now i have milk and eggs delivered, I have no reason to go shopping on a whim, so temptation is removed.
I still can't live as cheaply as my son, who has another year of uni before he qualifies and lives on a bursary and NHS bank work at weekends. He can manage on £15 a week for groceries, is veggie, and eats lots of lentils, beans and pulses, buys from food cooperatives, and picks up a mixed bag of fruit and veg from a friendly asian greengrocer who makes up the bags fresh every day for £2, containing misshaped root veg and the cheapest produce that is in season. A fraction of supermarket prices, and a great idea. They sell as quickly as he puts them out on his stall. Mind you, son's motive for living cheaply is so he can socialise with his mates and be able to buy a few rounds!