Sainsbury's, IME, tend to have lots of little reduced cabinets, practically one per aisle, but hidden away so you have to look for them; Tescos usually have a fridge one, a bread one and a not-fridge one, and they're normally in a pretty obvious place.

The Kwop (as my mother would pronounce it) tend to go down the Tesco route.

(don't worry if you tag stuff wrong, these things can be easily sorted out :) )