I do shop cheaply and make Chickens/roasts last for 3-4 days. There are 2 big eating adults here and quite a hungry 18mo. It only works with lots of cheaper bulking ingredients.
Sunday - Roast Chicken (large one for about £6) with sausage meat stuffing (cheap pack of sausage meat £1, bread crumbs, chopped onion, celery, apple, black pepper and sage baked in a loaf tin). i only serve the dark meat - so a large thigh each (and i would do a leg each for your 9 and 7yo and a some of the bits for the 1yo) with the skin on, and a couple of slices of stuffing, pots, parsnips, yorkshire, carrots, broc/peas/cauli cheese/cabbage. I also do a cheap pudding like apple crumble/rice pudding.
If people ask for more meat, then the answer is no, that is a big enough meal and there is pudding.
i then dismantle the chicken without anyone picking at it. i cut the breast meat into inch chunks, then pick every scrap of meat i can off the carcass. this all goes into an ice cream tub - no one is allowed to pick at.
Meals i get are 2 of these - Chicken and stuffing hash, mash and leftover gravy (made in the roasting tin) and steamed veg. Chicken and chickpea biriani and veg curry - Chicken and chorizo/prawn paella - Chicken and kabanos/chorizo pasta - Chicken and bacon pie.
4th meal is a meat free soup/risotto. i make a stock with the bones and veg trimmings which i keep in the fridge from the previous week. then either use it for a minestrone/tomato and red lentil soup, served with cheese on toast. Or a mushroom and pea/courgette risotto.
i buy the cooking/value packs of bacon from sainsbury for £1.10 and get enough for a pasta bake, chunks for the chicken and bacon pie, quiche lorraine/frittata for lunch.
If i get a large leg of lamb at a reasonable price, i get 3-4 meals out. Similar roast (not stuffing tho) to the Chicken. Then i mince 2/3 of the leftover lamb and do a lamb and red lentil mousaka served with a greek salad and pitta bread. A shepherds pie with mushrooms, carrots, onion, celery with a mash and cheese topping and leftover gravy made in the roasting pan from Sunday. Then i boil up the bone and veg trimmings (onion, carrot and celery bums a bay leaf and peppercorns) and use the stock and last 1/3 of lamb diced finely for a scotch broth and crusty warm rolls.
A piece of Beef = 3 meals (because no stock for soup). Roast. A beef an mushroom stroganoff and the rest i mince and make bolognese/meatballs mixed with some minced pork.
A piece of pork = 3 dinners. Roasted. Then sliced and cooked with onions mustard and cream, served with mash and veg. Egg fried rice with a handful of frozen prawns or chicken.
Gammon = 3 meals. Roast. Pasta, ham and cauli cheese. Cold with baked potatoes and salad.
Then there's mince. I do a big chilli and rice served with pittas. The following day we have enchiladas with the left overs (chilli and rice mixed together with a tin of mixed beans and sweetcorn/cubed sweet potato stuffed into wraps, a tin of tomatoes and a chopped large onion in the bottom of a baking dish and wraps layered on the top, topped with cheese and baked served with salad)
I also make tinned/smoked mackerel burgers and salad and pot wedges.
We eat porridge made with full milk for breakfast. Lunches are usually soup and sandwiches, baked potatoes, pasta and pesto, or left over leftovers!
I also make banana/apple/sultana (whatever fruit is going) loaves for tea time/lunch treats.
This is not a diet if you are low carbing or trying to lose weight. But we are all healthy and do lots of exercise. I spend about £150 a month.