So now to the academic stuff!
I see that, once you had set your mind on classics, you attended the Academus summer school online.
https://www.academuseducation.co.uk/summerschoolI see it's even open for students from the age of 13. There is lots of outreach for Classics. This is because few people get the chance to study ancient Greek and Latin outside grammar and private schools, and you may easily get hooked if you try it! This was a great introduction for you and let you edge a little bit further into that ancient world you had so loved as a child. That keenness ("I couldn't leave (the topics) out of my PS") shows how worthwhile these courses can be, especially in a subject you may vaguely like but want to try. It's also important, if you have not learnt Greek or Latin at school, to meet people who are in the same boat and with whom you can discuss your newfound interests.
I see you have wandered down just about every academic route you can to pursue your subject. There are novels, plays poetry, history and podcasts to explore and fall in love with. Anyone who applies for Oxford should fully immerse themselves in the subject, in whatever way they possibly can.
I notice that "preparing for the CLAT (Oxford Classics admissions test) was so much fun". This is another common theme with offer holders. Nobody is forcing them to do the past papers with a gun to their head. It's not a chore (though to the outsider, a Latin test might well be). It's a challenge to be enjoyed and relished. You have also brushed up your Latin and Greek grammar as well as language (Oxford loves grammar tests).
I see you chose Exeter college (my elder son's alma mater). It's the most beautiful college in Oxford, in my opinion. Wait until you sit on the mound with my avatar, the Radcliffe Camera, lit up at night and you'll know what I mean. As for the beautiful chapel, don't get me started on that.
Exeter is noted for English. Look at the writers who have graced its glorious quads
https://www.exeter.ox.ac.uk/alumni/notable-alumni/I recall my son doing the telethon (raising money for Exeter at Christmas by phoning alumni). Sir Phillip Pullman came to say hi, and took all the telecon bods out for afternoon tea at Quod.
It's very interesting that you practised talking through your ideas with your sister. As you say, it's important to formulate your thoughts out loud.
Also, to look at the camera rather than the screen. This may make you feel less nervous.
I hope you will keep in touch with your wonderful teacher. She will want to know all about your English course.
Also (no pressure) but at Exeter, famous authors have a brass plaque with their name on, affixed to the doors of their former rooms.
Just sayin'...
@edie__r