I shop in Sainsbury's and spend about £100 per week when it's 4 adults at home, and about £50-60 per week when it's just DH and I, and we eat really, really well. This is 3 meals per day each, plus all household and toiletries except toilet rolls (WGAC Subscription), it excludes wine (except for the odd bottle) and it excludes most of the pet food which we bulk buy (but does include pet treats).
There's a skill involved in meal planning, budgeting and scratch cooking, but sadly many people are just too rushed off their feet and don't have the time to invest in proper planning.
Breakfasts we have cereal (own brand fruit and fibre) or porridge (from oats) or egg, or toast.
Lunches are leftovers or homemade soups or cheese/egg/tomato/mushroom/bbeans etc on toast or omelettes, salad, avo on toast etc in summer.
Meals are a variety of meat meal and veggie meals, all planned and nutritionally well balanced. Cooked leftovers (in the dish, not plate scraps which are binned) are saved for another meal, leftover ingredients are used to make soups or frozen as appropriate. We waste nothing!
Fruit and veg is in season and basics - oranges/apples/bananas are a good price all year round - berries/plums/peaches etc get added only when in season. Ditto with veg, I'll meal plan around seasonal veg, but frozen peas/broccoli/carrots are a decent price year round.
I'm also fortunate enough that I have plenty of funds available to buy in bulk if something is on a fantastic deal, which works out cheaper overall.
We buy own brand and basic unprocessed ingredients where possible.
Toiletries and household items tend to be unbranded and bought in the bigger value sizes (although I check the per KG price as bigger isn't always cheaper).
Drinks are dilute squash, water, tea or filter coffee.