That's a boring, played-out stereotype that wasn't even true 30 years ago, let alone now. If you've never set foot in a UK supermarket I could see you perhaps still languishing under this delusion.
I literally just came back from a month in Poland, and UK food prices in supermarkets are just as low if not lower. Certainly Aldi prices easily beat Polish supermarket prices on nearly everything, maybe with the exception of baked goods.
Don't get me wrong - M&S and Sainsburys are very expensive places to shop. But I don't see the quality at Morrisons or Asda or yes, even Aldi as being any worse and the prices are very low. Go to France or Germany and try to compare, I can bet that for your average buyer groceries will be cheaper.
Its true i can't eat steak 4 nights a week as god intended but we manage to scratch cook 3 meals a day for 2 people for £70 a week, £85 with a wine pairing.
If you want to forgo eight different vegetables and four different proteins im sure you can do it for less.
I know too many people complaining "food is expensive" when all they live off is gas mark 6 / 25 mins beige rubbish.
