I've also just finished the Access To Degree Studies course and will be starting my degree with the University of Aberdeen this September.
The course is absolutely fantastic for people who are willing to put in the work required of them. My only tip for people taking on the course is to really focus and get everything you can out of the experience. Access students have a huge advantage over school-leavers as they already know the grading systems, the referencing systems, how the exams are run, how to use the student portal, how to use blackboard and where things are on campus to name a few. I didn't find the content particularly tough, however that's because I put the work in. Many people in my classes really struggled and ended up being left disappointed with their grades because they saw it as an easy ride and a free pass into uni. It is not!
The course staff are also really friendly and helpful, plus you get an opportunity to give anonymous feedback on all of your tutors/lecturers.
As for the interview, I don't remember having to bring anything with me. The interview was incredibly informal and relaxed, so don't stress about that. We spent a lot of time talking about why I felt the course would benefit me etc. We also talked about the classes I wanted to do and the degree I wanted to progress onto.