A Level Bio - SNAB

Basically, I’m rlly worried abt exams. I’ve been having to teach myself the content for a while now as we barely get taught in lesson and in my last mock paper 1 I got a high C. I’ve found at least 8 marks that have been missed which would put me up to a high B and ig i’m just really scared if that kind of thing actually happening in my exams. I try so hard w learning exam technique and teaching myself the content and have a tutor once a week but i feel like it’s just not enough. Any tips for SNAB Bio?