To my knowledge, unless anyone knows of resident shoals, all UK bass winter in the western approaches in deep water where the consistent temperature of the deeper water prepares them for spawning. This is where the French trawl for them in pairs because it is literally like shooting fish in a barrel once you locate a shoal. Also lots of dolphin by-catch which gets widely reported when they turn up dead on our beaches. Personally I have neither seen or shot bass any earlier than April on the mainland, anywhere. I know you can in the Channel Islands and I'm sure smaller ones are about in the estuaries which are designated nurseries so you can't catch them. I'm sure loads of people will now respond saying how many bass they've caught in Winter months. If so, they can tell you where to catch 'em