As per me if you want to promote site for USA, UK or any country than you have do all the work relared to that country for e.g. if you do Article submission than do submission in UK sites if you want traffic from UK.
For complete organic traffic you have to do all the task of OFF and ON page optimization but keep your target all UK sites whether its article, S.B., Blogs, Forums etc..
One more thing try to get backlinks from high authority site say PR
4, more than this so that you get quality backlinks and if you do in relevant site than it will be more beneficial for you.