It might be more expensive, but I find you have a much higher degree of variation in the UK; most importantly in the type of weather conditions you experience.
For high degrees of variation, go to Northern California
What good does 1200 BKN -RADZ do for a pre-PPL student ? That he learns that his day-off is now wasted ?
Actually, the weather in the US has much more extreme variations than in the UK (if that is what floats your boat).
Also, if you spend longer doing your training, you will encounter changes in the seasons and there's more change of experiencing different circumstances.
I'm sorry but that is the BIGGEST CLAPTRAP I have heard since long. It is much more efficient to get your license over and done with in a relatively short period abroad and then use an instructor on an occasional basis in the UK.
If you're a beginning pilot and have to cancel three times in a row because of sh1te UK weather / sh1te aircraft / sh1te disorganised FTO, you end up needing more total time (and more £££) to get the ticket.