I don't know about today's prices, but when I was a single mother I did this, then again when DH was on a zero hours contract and I was just pulling in odd hours as a barmaid. We didn't know what we'd be earning from one week to the next.
Tesco at the time had a £25 basket minimum (still miss it) and I had a delivery saver pass which wasn't prohibitive.
So on a bad week I'd spend £25 but on a good week it'd be £35. I'd sit for an hour on Sunday evening and stock take the cupboards and meal plan. Not sure we were quite on £1 a day per head but for years it wasn't much more
Most things that are Tesco Value are fine, they actually just have less added sugar and salt, so the likes of pasta sauce were fine with an extra sprinkle of herbs and garlic.
Off the top of my head, we ate things like a basic pasta with frozen spinach and peas and value cream cheese added plus a 30p garlic baguette. Soup is cheap to make - I remember using a lot of celeriac at one point which was very cheap at the time. Cabbage, potatoes and bacon - Tesco did 7kg of spuds for I think £4. Cabbage is pennies, fry it up with an onion and bits of cooking bacon.
Root veg casserole topped with cheesy mash and breadcrumbs - again, swede and turnips are pennies
Sweetcorn fritters with green beans/salad
We always had a roast and made the chicken last - the reason why the Mumsnet chicken is seen as an exaggeration is because people want the equivalent of breast meat every day, but if you simply have less meat it's doable - a handful of chicken as an addition to pasta for example, boil up the carcass for stock.
Fruit cake and banana cake for snacks and lunchboxes. Rice pudding and apple crumble for puddings.
We live 20 miles from the supermarket and apart from the village shop and the Tesco deliveries had no access to wholesalers etc, no car either so no buying in bulk
Peppers stuffed with couscous and olives was another one that was cheaper than you'd think.
Lentil loaf with frozen veg and Yorkshire puds
My bible was Rose Elliott's Vegetarian Cookbook from the 80s. Lots of good family recipes for very cheap. We weren't wholly veggie but ate limited meat.
Value bread, cream cheese and cucumber for packed lunch sandwiches, pita, grated carrot and cheese ditto
DC ate better than many of the better off kids who were always bringing chocolate and crisps and prepackaged sandwiches to school.
When our finances improved, I rested on my laurels and became a bit overweight because I got lazy and we started eating far more meat. We all felt unhealthy and sluggish and have actually gone back to a moderated version of our previous poverty diet (soup and omelette nights made with veggie leftovers,no junky treats unless we bake them)
I wouldn't like to go back to it purely because although we are far from rich, it's obviously nicer to be able to buy the big punnets of blueberries for the DC without worrying too much and all that, but there's a lot of habits I've kept and certain things I won't pay for the branded product. If I had to go back and shop and eat like that again it would be a bit of a PITA but the absolute least of my worries. I'm fairly confident now in my abilities to make do and to live under a hen.
Tbh it pisses me off a bit on MN when people basically play the tiny violins and virtue signal over the thicko poor people and their cheap chicken nuggets and super noodles. Obviously there are people who eat absolute junk from dawn to dusk, but it's more complex than that, and there are plenty of poor people who are quite capable of making soup, roasting a chicken and boiling an egg, and take pride in doing so. Our manual jobs also meant we were fit and slim.
In fact the most unhealthy family I know were wealthy middle class- they had a different takeaway every night of the week. There was Chinese night, chippy night, Indian night, McDonald's night. A takeaway for a family of four around here will easily set you back £20- poor people can't afford that!