CJB, thanks for asking about DS1. He's happy and settled and has made some friends, although they're not really on his wavelength but are good to hang out with.
He also has some second year connections via an old school friend and they're more like-minded (and his age group too, given his gap year) but he's hoping to find more friends from his own year group - probably next year now when there'll be more possibilities for interaction with people outside of his college.
Lots of people are busy with exams this term and no one he knows in college is interested in things like attending Formal Halls and doing 'traditional Cambridge things' which he'd love to do. However, he's got people he's happy to share accommodation with next year and he's joined various societies that he hopes will bring him new connections next year when things are a bit more normal (well, we hope they will be).
Compared to his brother at Oxford, he's having a much 'lighter' time academically, although still working hard of course. This term a different supervisor has also not marked any of the essays at all, all term, for the paper in which he's about to have an exam - but DS1 feels it doesn't really matter and is chilled out about it.
I'm still gasping at this myself, as a supervisor in his first term took until mid way through the next term to mark essays from that first term and I really can't understand it at all, even though I realise all supervisors are obviously very busy.....(deep breath as I realise I could now go on a rant!). Anyway, I guess it's all about what you do yourself as a student and perhaps feedback from marked work is indeed less necessary? Hopefully he'll do OK.