Generally our experience is that the sort of international London teenagers who have a genuine choice of going to University in the US or staying in the UK will opt for the US. Top Universities there are perceived to be better and campus life more stimulating. There is no way any parent could send an unwilling child to a US university if they did not want to go. The extracurricular requirements and the application process are just too demanding.
Of course there is drinking. But pubs and restaurants won't serve you, the campus police can be strict and woe betide you if you get caught with booze in your car.
From what we have seen it is absolute not uncommon for British students to face the sort of issues described by OP. Or desired by Ylfa's DD. (Horses for courses. One of DDs fist year flatmates was a similar age. She dropped out of Imperial in order to reapply to somewhere with a bigger party culture.) When I posted about problems three years ago, it was interesting. Quite a lot of posters pooh-poohed the idea, suggesting that DD was simply a Billy no Mates, so effectively, deserved what she got. At the same time I received quite a lot of DMs suggesting that DDs experience was, sadly, not unique. And tragically a boy in the same hall as her, took his own life, one of several that year.
There was one poster who was particularly brutal, then it transpired that it was a full decade since her DD had been a fresher. Things have changed. Drugs are stronger, country line distribution more efficient, date rape drugs are more prevalent, students - the first to have grown up with smart phones and social media - are arguably more anxious.
It's not everyone. But there are issues, and I think these issues need to be addressed. I have a lot of Asian friends (and indeed speak an Asian language) and am more than aware of their concerns. Some posters may reject the idea of British parents, with choice, preferring the US. I can confirm that Asian parents, paying three times what UK student pay, factor these problems in when making a decision. (They also factor in Trump's approach to foreign students which is why UK numbers of overseas students may be holding up for now - but after the next election I think Universities may start realising that 18 year olds are adults but are still owed some duty of care.)