@merryhouse
Stuffed lamb hearts cooked with red wine in the slow cooker, mash, veg and gravy made from the cooking juices.
I know people balk at eating hearts but we get enough for the four of us for £2.70ish. Just remember not to try to eat the top tubey bits and it's actually quite tasty, and meatlike in texture nothing like liver or kidney.
@merryhouse you're a heart lover too! Braised lamb hearts with carrots and mash is our macabre Valentine's dinner. I agree they're really meaty but completely tender (I cut the tubes out with scissors) as long as you slow cook them and when you slice them they don't look like hearts - they just look like sliced meat and they taste like lamb. Because no one wants them they're about 20p each which is enough for one person with all the rest of the stuff. Your best bet is the butchers especially if you have a lot of Turkish or north African people nearby.
I love kidneys - they do not taste like wee and are incredibly cheap and quick to cook with recipes on the internet. I also love liver but especially chicken livers fried with chopped onion and bacon cut in matchsticks then simmered in a bit of stock on mashed potato. Do them with frozen peas which you can cook in the same pan. They're really delicate - better than lamb or pig liver. They're cheap fresh but even cheaper frozen. Sainsbury's sells them for about 50p for 250g but I bet other places do them cheaper. Don't overcook them. Eat them pink in the middle - they won't hurt you.
All these things are really meaty and low fat and will fill you up. They're also richer than other meat in iron so good if you're pregnant or anaemic and don't bung you up like iron supplement pills.
I accept though that most people won't eat offal. Fresh pork is a really good buy as is chicken. A whole chicken works out much cheaper than portions. You don't have to eat it whole but cut it up into six or eight pieces and put what you don't need yet in the freezer. You'll see how easy it is to do on the internet and find recipes. Save the wings to fry crispy - you never get raw wings in the supermarket. You also get the skin. Supermarkets take the skin off because they can make other things out of it. I like skin but if you don't, throw it away. I don't bother with making stock or soup out of the bones but people do.
Same with other meat. It's cheaper to buy a shoulder of lamb or joint of pork and cut it into cubes for casseroles rather than ready prepared cubes.
I find kIppers too strong but I do like fresh or smoked mackerel. Fresh mackerel looks and tastes beautiful and it's so cheap - and one of those oily fish you're supposed to eat.And tinned tuna and salmon.
Buy yellow sticker fresh meat. I really don't understand why people are too embarrassed, especially now. I like ready meals and will get them because they're nice but your best buys are meat - especially if you get a fillet steak or something else you wouldn't normally buy.
I've started getting all kinds of frozen food - boneless fillets of salmon, cod or haddock. You can bake them in foil with a bit of butter and have them with rice, potatoes, couscous. I also like bags of uncooked frozen jumbo king prawns (shell on) or a seafood mix of squid, prawns and little queen scallops. You can make risotto or paella with some frozen peas. Also a handful of frozen sliced mixed peppers - though they've run out lately. Apparently it's down to the increased cost of heating the greenhouses they're grown in.I can still get the fresh ones but they are leaping in price.
Frozen mince is a lot cheaper than fresh and just as good so long as you watch out. I shop in Sainsbury's all the time because that's my nearest supermarket. Their own brand bags of frozen mince taste the same and have the same fat content as the fresh stuff. It looks like pink worms in the bag but is honestly exactly the same. You can cook it from frozen and reseal the bag so it's miles more economical.
Tinned beans like red kidney, butter, cannelini etc are better than dried because though dried are cheaper the cost of fuel is going up. I like dried lentils though - not so much the red that go to mush but the green ones. Puy ones are best and not that expensive if you're not eating that much meat.
Cabbage and carrots are cheap and last. Broccoli is cheap but goes yellow quickly. Slice the stems for stir fries. I never buy potatoes full price. My best is 24p for 2.5kg.
Sorry to chew everyone's ear off about this. I love it and everyone needs to save money now. Thanks if you've got this far 
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And thanks to everyone for such great tips.