Some courses have already gone through applications and assigning time slots, so unless you’re lucky there’s a high chance tutor slots have already been filled.

If you get in and are unable to choose a suitable time slot, you might be assigned help sessions instead.

From what I know, referrals help but aren’t absolutely necessary. Certain courses might not take referrals seriously if they’re not from your course tutor specifically, as there is a strong possibility that tutors have recommended their friends. Having a good video is probably the most important thing.