Hi OP, ds is at Imperial and just finishing his first year. He's had a fab time. His roommate (a friend before from school) does physics and he seems to have a lot of time for his hobbies (one in particular takes up a lot of time). Physics is actually seen by some of them as an easy course (crazy!).
Ds has plenty of regular small group tutor time (8 in a group). This is really important. I'd say him and his friend from school are very clever (both got 4 x A stars at A level and did EPQs etc). For ds, the course is perfectly manageable and quite fun. He loves the extra challenges in his subjects but has still managed to continue a lot of hobbies, go to a couple of gigs, join several new societies and commit a lot of time to being a writer for the aforementioned Felix (due to be announced as an editor very soon).
London has everything and he does a martial art and plays a particular card game at a club off campus. He doesn't drink and is more motivated about things like sustainability and plant-based-uni initiatives etc.
I was at Imperial yesterday and it was busy with students milling and a camp out on the Palestine issue, with a few students living in tents. Also, every week, there's a food market, which I hear is quite good too.
I couldn't be happier with his experience. Nevertheless, he does tell me there are a few students he knows who don't seem to have hobbies or go out much. I think this depends on personality and also ability to cope with the course.