Commonly available chocolate in the UK isn't much better than chocolate in the US. Manufacturers in both countries skimp on the ingredients which make "chocolate", chocolate.
You can, with a deep wallet and if you are suitably located, go to a store like Selfridges and buy a wide range of imports (IMO Dutch and Swiss are the best). One of the perks I used to enjoy as a regular customer there was getting an invite a couple of times a year to a chocoholics evening. Perhaps a dozen international manufacturers showcased their best products and for a couple of hours or until you got sick, you could stroll around gorging yourself - completely for free - on whatever caught your eye
