@beethecrackon24995 just reading the thread as I was in your position 4 and 2 years ago.
DD1 is now a 4th year NatSci at C in her Masters year and is coincidentally good friends with @goodbyestranger's DS4 from school. Your comment on the chapel choir was what prompted me to reply. Whilst students often apply to their own college choir, they don't have to do that. DD's college choir has a fairly big time commitment as they do a lot of services & rehearsal in non-Covid times. She didn't apply in year 1 as she playing in an orchestra & was coxing one of her college boats, but in year 2 went for a chat with the Director of Music & sang for them - DD had sung in a mixed choir right through secondary school. DoM said she was a decent singer and suggested she went to the next college along the road. DoM emailed their counterpart and following a quick audition DD has been singing there for the last 2 years. I know another student from the same school is at G&C but sings in Johns choir as she & DD have done some joint services.
Good luck to all parents & offspring. It's a rollercoaster ride. Having had one DD make it and one rejected post interview, it's tough but they will all end up somewhere and if like my DDs, will thoroughly enjoy the experience.