Agreed on Hershey's chocolate being a bit revolting - and I'm a Yank.

I've not spent any time to speak of in the UK, but have been in NZ for a few extended stays. My hands-down favorite there was Whittaker's. IMO much better than Cadbury's or Nestle (but I'm a dark chocolate guy)

BTW, in NZ, Cadbury claims to not make a dark chocolate bar, but I discovered that they do sell an 'energy' bar that's pretty close...