Waitrose - expensive and not as good as it used to be. Smaller national chain
M&S - expensive, but not as expensive as you think, top quality, smaller national chain
Sainsbury's - big national chain most expensive of the "big" supermarkets.
Morrisons - got very expensive since it was recently taken over, gone very downhill, Sir Ken would be turning in his grave
Tesco - biggest supermarket - generally good quality, reasonably priced
Asda - big chain, good prices, reasonable quality
Aldi - discounter - cheap, good quality
Lidl - discounter - cheap, not as good as Aldi
Co-op - convenience store, very, very expensive. Good ethics fairttade etc.