You can't fake your way into the upper class in the UK, because they all know each other already. As for behaviour, dress and speech, the standard books are:
* Noblesse Oblige[0] Mostly about vocabulary, and very outdated (1950s)
* The English Gentleman[1] Only about aristocratic men, and comedic in style
* Class: A View from Middle England (Jilly Cooper) Very 1970s
* Watching the English[2] Not specifically about social class, but class comes up a lot.