I have converted my share of US trained intensive course PPL's to join British clubs.
BEagle has neatly identified what appear to be the main common problem areas.
Unusual attitude recovery techniques in addition to spiral dive are often absent - not a strict syllabus item but very quick andeasy to throw it into stalling lesson 3 or steep turns...
PFL's that are fine in the wide open plains of the US but of little value when trying to put the aircraft into Farmer Palmers 5 acre top pasture field replete with fine oak trees and ManWebs plumbing at the far end.
A propensity to stare inside continually chasing needles rather then really really nail the visual attitude using dead flies, canopy frame and cowling/horizon cues. In addition an over dependence on radio nav aids.
Navigation which is fixated on slavishly following a track line rather than quantifying error and compensating appropriately i.e. closing angle to regain in equal time OR at destination.
I would also add that standards of r/t are very different in the UK and the airspace is more complex. Telling me how you laned a C152 at LAX does nothing to impress me as a chimp can follow radar vectors in a TMA. You trying scudding around the UK with a 3000' cloudbase hoping from an air/ground operator at Little Piddlington to negotiating a MATZ clearance then talking to a major international airport for a VFR transit or willing to take a Special VFR or maybe a RAS off them before emerging the other side to find no-one to talk to than London FIS who a real busy and can't help you very much with anything other than the regional pressure setting and the time of day... UK airpsace is crowded and controllers rightly demand a competent command of correct RT and it is very hard to master this requirement if your RT has been developed in a radar everywhere just treat it like a telephone atmosphere.
Make sure you budget for 4 hours check out on your return from the US. The club you join may well not offer the same type of aircraft that you trained on in the US plus the 'fit' of it will be different, you will be very low time so will require extended local procedures tuition plus a decen club instructor will want to put you through a skills test of his own before signing you off.
If you train at your local school/club/airfield then post skill test no checkout will be required, no local area briefing and no conversion of aircraft model/varient. This saves money. You will also feel a lot more confident and enjoy your license more from day one.
You really don't want to be nervous, unsure of procedures, frequencies and have to map read contantly when you've just got you license and inevitably you are taking all your family and mates flying.... Plus the 100 hours post skilltest are the most dangerous and you need the most knowledge and experience on your side as possible....
I was talking to someone recently at work who has been stateside for a PPL course and in the end it cost £3,400 by the time they were able to exercise that licence down the road at the local flying club.
There are several flying schools in the UK which offer PPL courses for less than that. Witht he current high dollar low pound exchange rate the savings are very marginal. It becomes more worthwhile if you are also building hours ready for the CPL. But then you will find doing the CPL course and skilltest in the UK quite hard as you are now expected to operate to a safe Commercial standard with all the weaknesses I listed earlier. You are likley therefore to need some extra hours tuition on the CPL course. At circa £180 per hour you can rapidly eat into any saving you made going Stateside...
Good luck,
WWW
ps what have you done to research prices? I hope you've contacted all your local flying schools and talked to them about package discounts/free membership/IMC,Multi,IR,CPL course availability/going all the way with them to commerical licenses therefore can I have the CFI as instructor from day one please.... OR have you just read the glossy adverts in the back of Pilot/Flyer....???