I would have thought it was worthwhile having some extra lessons in the US if you can get the visa resolved.
The hours required in the UK to get your PPL are a minimum. The important thing is your competence. If you are missing lots of lessons due to UK weather then you will likely go over the minimum required hours before you become competent.
Some refresher training in the US won't go amiss and while it might not count to your UK PPL it will mean that you will need less hours over and above the minimum back in the UK.
There are some differences in air law, proceedures etc, but takeoff, flying and landing are just the same. Also, I think you will find it easier if you fly the same type of aircraft.
ZA