English interview help

I've got an interview at Cambridge soon but I'm worried about the part of the process where they'll give me an unseen passage and talk to me about it. I'd like to try to prepare for this more by practicing on poems and extracts at home but I'm struggling to find websites where past applicants post the extracts they were given, or any websites that have sample texts of the kind Cambridge will use. Can anyone recommend a way to practice?

The whole point of giving you an unseen passage is to test your ability in how you deal with something you are not familiar with. It's not only for English but they have similar style of test/question at interviews for all other courses.
There's absolutely no need to produce perfect answers/analysis on unseen pieces. That is NOT what they're after. They just want to see how you 'think' and how you 'apply' your knowledge on new things, rather than just checking what you know already.
It's very important to them because it's one way of checking how you'll cope in supervisions which is a very important part of their teaching.
So frankly, if you can't cope with unseen pieces without preparing for them beforehand, you'll not be able to gain much from your future supervisions, which means maybe Cambridge's style of teaching is not a right kind for you.

So don't worry about it. Preparing for it is exactly what they don't want you to do. As long as you're on top of what you've already learned at school and extra things you might've explored beyond your regular curriculum (sort of things you've mentioned in your PS/SAQ), you will be fine. Honestly.
I mean, the interviewers are some of the top academics in the field, if they think you've already seen/known the 'unseen' piece, they can easily test you on something else that's you definitely haven't seen before.

Congratulations for getting the interview and good luck.

Oh I don't mean that I want to try to cheat and see the unseen passage they'll give me haha, I understand why they do it. I just want to test and reassure myself that I can do it if you know what I mean? But you're right, I should be less worried, thanks for the reply

I know some websites/resources which offer past interview questions and analysis but I'm not sure if it will be specific to your college or whether they have the kind of extracts you want. You can PM me though if interested.