Do I need a marital visa right away to return with my new wife to the UK, as she is a citizen of London?

I am an American 2x felon (a drug charge in 2000 and a theft charge in 2006). My fiancee is a UK citizen, and we are planning to meet in Cyprus. I plan on marrying her over there, and I wish to return to the London with her afterwards. I've heard that London is really strict on who they let into their country, but I've also heard that they like to keep families (married couples) together. Would I really need to get a marital visa before I can enter, or would they just respect our marriage license? I hope you guys can help me out here... Thanks in advance!