The biggest problem that you may find is with instructors in the UK who are prejudiced against US trained flyers. Phone around and find an instructor who trained in the USA otherwise the UK trained instructor may want to prove to you that you didn't learn a thing in the USA. In the UK, it seems that you really need to imagine that you are broadcasting a documentary and include things in your RT like reading back the QNH, QFE, number of people on board, mothers maiden name and anything else which may be of interest to the controller as apposed to the short and to the point US RT which you have learned. Also, UK pilots seem to be reluctant to land and prefer to check out that the vis is within VFR limits by making the pattern about 5 miles radius of the airport. Maybe they are just leaving room for 747's to join them!
If you trained at a non towered airport then you are likely to have serious difficulties switching to flying from a towered airfield anyway.
Be prepared for the shock at the end when you get presented with bills for around 150 quid for an hours jolly around with an instructor in the UK!
One last point, a PPL is only evidence that you have achieved a basic standard of airmanship. A club that doesn't know you will want to ensure that you are going to return their airplane safely so more hours flying is going to be a pre-requisit to being set lose with their aircraft.