Having done multiple flying courses in the UK and US over 30 years, my advice would be not to even contemplate combining a holiday with a flying course. Just be totally dedicated to it.
But, do go for somewhere with consistently good weather, as that will up your flying rate and improve enormously the chances of getting it all done in the time allocated. Britain will teach you to fly in the environment you're training for, but at the same time, it'll also lose you more days due to weather.
My local club at White Waltham (West London Aero Club, just outside Maidenhead) is a nice spot with an excellent reputation. You could do worse than have a chat with them. I believe that Aviation South West at Exeter are pretty good at the moment also from what I've heard over the last few years, and that far South West likely to give consistently pretty good weather in the summer, whilst also learning in British weather and airspace.
G