I'm using WebHostingBuzz in the US but their top man is located in London with another set of servers (to serve the UK and Europe). As I've had excellent service, I can recommend them highly.
Additionally, you may want to checkout their "specialist hosting" packages as one of mine is for a client who demanded the extra processing requirements Joomla needs. WP's design is so modular it also requires a great deal of CPU power to play "step and fetch it" for all the pieces it must acquire to assemble a page.
Lastly, a warning: WP is great at updating their software but you MUST keep up to date with them as they move along quickly. If you don't, you'll be left with gaping security holes and surely will have your site hacked.