because you're going to come back to Europe and be utterly confused by the way things are done over here and how complex and busy our compact airspace is.
I don't think so.
Yes there are differences, like in the USA you can transit Class D airspace with just a radio contact, but only a dumb pilot will get caught by that. You have to get clued up on UK regs and procedures before you fly here, but you don't need 45 hours to do that.
UK airspace is way less busy than US airspace. They have about 10x more GA over there.
US pilot training is on the whole very thorough and IMHO better than UK training.
UK and European airspace is indeed a mess compared to the US structure, but that's just a case of getting the maps, and a decent GPS.
One thing I would strongly recommend is to do the PPL in the one school in southern California, where you can do both a JAA PPL and a FAA PPL at the same time. One can do this "dual" stuff at 6 or so Florida schools also, but S. Cal. is a lot nicer
Don't just do a JAA PPL, and obviously don't just do an FAA PPL. The present system where one can fly a G-reg worldwide on an FAA PPL is proposed to be killed by EASA in April 2012.