In order to play on US servers from EU, all you have to do is go into your wow folder, there is a file called "realmlist", open it up and change the "eu" to "us" and then save the file.

I did have some problems with some of the EU game clients becuase of a language pack.

This definately works with UK version of wow because i use it in the oposite way to access EU accounts from the US and i know guys that do the opposite.

So it might be easier for you to install a UK version or install the UK english pak that is compatable with the US client.