Approved Foods are currently saving us a fortune!
You do need storage space as you end up with vast quantities of random packets, but we now do a monthly AF & try not to buy any other curry/chilli/stir fry/table sauces.
Also, buy an enormous bag of red lentils & use to replace/eke out mince/Quorn in everything. & cheapo frozen mixed veg from Asda/Morrisons.
I make an enormous 'student style' veg curry once a week - sweat onions, peppers & any other veg that was on offer, add a good handful or two of lentils, a couple of jars of whatever curry sauce we've got in the AF cupboard, tinned tomatoes (always get saver brands for chopped toms), simmer for half an hour, chuck in a bag of frozen veg & a few handfuls of spinach from the garden. Any leftover cooked veg goes in too. Basically, I just keep chucking stuff in until the big saucepan is full.
We eat a third of it (2 adults, 3 dc) then I freeze what's left - it will do at least two more family meals, or lots of individual portions for me to take for lunch.
It's not wildly exciting, or haute cuisine, but the dc are getting a load of healthy veg, it is a very cheap way to feed everybody, & if I know I'm working late & won't have time to cook from scratch, I can just pull a tub out of the freezer in the morning.
I do an enormous veggie bolognese in a similar way - day one, spag bol, day two, shepherd's pie. Another third in the freezer.