Lentil and mince cottage pie
Veggie chilli with loads of canned beans, peppers, onions and rice (make a big vat of it for over 2 days)
Sausage casserole over 2 days (make 12 sausages do the 5 of you if possible, but if the kids are sporty/active etc, maybe buy 18) But chop each sausage into 5 or 6 pieces. Add loads of veg to it, chopped tomatoes, chopped some spuds to go into he casserole too. Add canned beans to it to pad it out more. Serve with bread.
Chickpea and spinach curry with rice
Mackerel pasta...buy 2/3 cans of mackerel, add it to a pan of peppers, onions, any other assorted veg. Buy a jar of sundried tomatoes
and add these too, along with chopped tomatoes. Serve with spaghetti.
For lunch sandwiches, don't buy sliced chicken for instance. Buy a whole raw chicken, cook it up and shred it (much cheaper)
Porridge for breakfast. Buy frozen berries to add to it.
Also, download the olio app to see if anyone is giving away food in your area.
It would be reasonably easy for me to do our weekly shop for 110 quid in aldi and buy plenty of meat and fish, without looking for "cheap" meals. Not sure about the prices in asda tho, so the above recipes are what I'd cook if I was trying to shave money off my aldi shop.