Ditto. Flying in the US is very different to the UK. (Note for the FAA enthusiasts, I didn't say better or worse, just different.)
If you complete your PPL in Florida, you'll almost certainly need a few hours extra training back in the UK, to get used to the different RT and airspace (particularly if you're planning to fly around the London TMA - it's very busy). And then, of course, there's the weather. Training in the UK can be incredibly frustrating (we've all been there) but it at least it will give you a good grounding for your future PPL flying.