Hi, it is one of the most difficult colleges to get into, but don't let that put you off! Just smash the competitiion
I was at Woosta (Worcester) studying music from 2007-2010 and was very close to the college chapel choir members. I know the current Senior Organ Scholar and some of the other choir members reasonably well. Indeed, my former tutorial partner is the current Director of Chapel Music who would have auditioned you!
So I can vouch for the college chapel choir being very friendly and welcoming, as well as (one of) the best mixed choir(s) in Oxford.
As for Woosta more generally: we have buildings going back to the 1200s, granted, but we're quite a relaxed college in general. We have a reputation of "work a bit hard, party seriously hard". Formall hall is quite formal in that there's lots of door-slamming, mallet-banging but once you get over the initial WTAF
moments, it becomes really hilarious and fun to be a part of
As for the demographic, it does shift on year to year. When I applied, we did have one of the highest private school ratios. I would, however, like to assure you that this is NOT going to affect you at all, as (what I presume to be?) a state school applicant. You honestly can't tell what kind of schools people have come from. I went in with a huge comp-educated chip on my shoulder and ended up living with people from top London private sixth forms and Kent boarding schools in my first year. They were really lovely, down-to-earth people who, yes, had been afforded more opportunities (up til that point) in life than me and had more money, but that made absolutely no difference whatsoever. Then, there was another friend of mine who spoke very well and seemed really confident, so I assumed he was from a top public school and never bothered inquiring as to where he'd come from. Half a year later, when I casually mentioned being comp-educated in passing conversation, he was like OMG TLG, ME TOOOOOOOO and I was like
So basically, you can't tell. In the unlikely event that you ever run into prejudice due to your background, you can either ignore such people quite easily (Woosta's size means you can easily either know everyone in your entire year group - or alternatively, you can be as anonymous as you like and avoid people easily!), educate such people, or - depending on what was said - report them to university authorities. Woosta takes such rare occasions of overt prejudice/discrimination pretty seriously
As for English there, I know quite a few English students from my time there and they all had a fantastic time! Some of the tutors have changed, I believe, so can't comment directly on that entirely. But DB and LA (presuming they are still there, at least) seemed to get on with their students and be stimulating people to be taught by!
Any questions, do feel free to ask me! If I can't answer, I will ask my darling college tutorial partner (current Director of Chapel Music) and get some answers for you