I am so sorry that you are going through this xx
When I had no money (ex H disappeared and emptied out our bank accounts), our church stepped in and helped us out with a £60 supermarket shopping voucher for some food. And I got a voucher for basic banks
But let me tell you my top tips
Buy chick peas - tinned or dried (dried- you have to soak over night), they bulk up protein and meat in your dish.
Buy spices and shop in Aldi's dry sections for sauces (jars bottles and tins) etc, frozen, and bakery sections, their tinned tomatoes are 28p
Buy your bread in Aldi's, pain au chocolates 8 for £1, part baked rolls 8 for 80p, And frozen chicken, veg and meat there if you can
You can get big packs of pasta and rice in Asda- I get the £4 huge pasta bag (it's about 50cm tall!) which is huge and lasts me 10 weeks
Make food like
Baked potatoes with butter baked beans and grated cheese on top
Pasta baked with some ham , jar of 60 p pasta baked, some grated cheese and sliced ham you tear up into it adding some frozen sweetcorn, peas or chopped spinach for veg into the pasta bake at the start. (We put foil over dish when in oven so pasta doesn't over brown)
You can buy pizza based (or use flour tortillas) to make our own cheap pizzas
Sausage hot pot- use a pack of sausages, cut up small, Fry lightly with bit of oil, onions and then put into a big saucepan with 2x tinned tomatoes with herbs, chopped garlic, some ground pepper and (rinsed well) tin of chick peas + some veg (tinned or frozen , like sweetcorn , peas, chopped spinach or small diced carrots, any that you have) , heat on low and add 50ml water + splash of soy sauce and put lid on - stir regularly . At same time cook pasta in a saucepan. After 20 mins drain and add in your cooked pasta to your cooking sauce/meat. Then 4 mins of more heating and stirring you can dish it up. That's a meal for 3 people for 2 days at about £4 for the lot.
Buy cheap dried noodles (50p - does about 2 meals), boil it for 5 minutes , whilst stir frying any left over chopped up meat from roasts (chopped up port or chicken or beef) or whatever cooked meat you have, add in frozen or tinned sweetcorn or peas to stir fry them quickly for about 5 mins then some big splashes of sweet chilli (1/4 of a bottle),(again 70p in Aldi's £1 in Asda) , splash of hot water from kettle , then stir in cooked noodles into your wok for a few minutes (making sure all cooked , mixed and warmed through) and you have a tasty meal (from left overs) for 4 ppl for less than £1.50 total.
So many recipes on fb groups - search those up- about eating for less. And how to stretch out meals. Try to add pulses (cooked lentils, chick peas , kidney beans) to all your meats to bulk out the protein.
Make packed lunches for children & for you. I bought 50 sachets of porridge for about £5 on Amazon - all made with a bit of milk and then had added chopped Bananas for a filling breakfast or snack after school.
You can ask your gas, water and electric providers for their cheap rates for those on low income.
I think you can apply for warm home grant to your provider which is worth about a £140 one off amount from your electric in winter
www.gov.uk/the-warm-home-discount-scheme
Buy second hand clothes or look on local fb selling pages or gumtree. I have loads of clothes now that I end up giving to charity shops but often say here's a bag of age x for £5-10 on fb and no one wants them even though is really £100s of great condition clothes. I'd be glad if someone said yes please!! To pay it forward ..,
Don't worry about buying much for Xmas- you can buy nice presents from cheap shops like home bargains or Poundland or from ebay. Your DCs won't know it's second hand. Cheapest place to buy toys for Xmas is local fb or facebay groups - sellers love it when people turn up as arranged! You can get such bargains
I hope some of this helps. Just trying to add To what has already been said