If you have the choice then I would suggest that you at least consider doing some of your hour building at SFC. Reason being that the airspace around the airfield is very busy and complicated also when it comes to doing your Navigation in the CPL you will be well adapt to the area and the terrain and possibly local airfields which to be honest is invaluable. Admittedly the weather can be an arse, then it can be anywhere but I guess.. 40 hours in the states can be done in 3 weeks, where as it might take you 4-5 in the Uk but you could end up spending the time you saved on getting used to flying around the SE England on your CPL.
I don't think anyone can tell you what to do especially when you could sit around SFC for 8 weeks trying to do your HB but in an idea world I would say do it at SFC and learn something from it rather than burning holes in the sky in the USA and not really doing anything constructive other than racking up the hours an avoiding other aircraft!