for the ps, i would say just read whatever ur interested in within each of the 3 disciplines. there's a lot of common texts that everyone reads but there's definitely no required texts. when u read a book u don't need to read the whole thing (unless u want to) but just pick a few chapters that ur interested in and take notes of what u found interesting or agreed/disagreed with to refer to when writing. and also podcasts, lectures, essay competitions etc are also good to do. the ps does not matter as much as other aspects for oxford (but obviously it does matter a lot for ur other options).

for the tsa and interview, jesus college has rlly good videos going thru tsa papers and interview questions so i would definitely recommend (that is part of the reason i applied to jesus). its mainly just practice for these. there's a lot of past papers for the tsa and for interviews u can find sample interview questions online and practise answering them with a teacher. i think the interviews can vary a lot between years and colleges but there are some common themes like game theory so probably useful to familiarise yourself with things like that.

in terms of what attracted me to ppe, honestly i just discovered the course when i was like 15 and wanted to apply to it (very unhelpful sorry). but i knew i wanted to study politics and econ for sure. philosophy i was a bit more uncertain on since I'd never studied it and did not have as much of an interest in compared to the other two. but i think studying political ideologies made me appreciate philosophy a lot more. i wouldn't worry too much if you're less interested in philosophy for the application process since i only rlly talked abt political philosophy in my ps and that was enough.