The level of chlorination in the UK is definitely lower than the US - after being there on holiday a few years ago, I really noticed it. However, I was quite impressed with my local water board, as they sent me a letter a few years ago to notify me that they were going to start adding chloramine to the water, so at least I was aware of it. I just switched to Prime, and have had no issues at all (it's actually working out cheaper than the previous water conditioner I was using). If you're not sure, ask the water board and use the whole "Freedom of Information" tactic, worth a go!
Brita filter jugs are great for filtering drinking water by the way - I find they make a huge difference to drinking water. I hate the taste of chlorine too.