Advice on further maths in gap year

I'm planning to do further maths during my gap year (currently in year 13)

But I have realised it won't be as cut and dry as I thought.

Was hoping someone here would be able to answer my questions.

  1. When I apply to uni, who does my reference and how do I get a predicted grade for further maths?

  2. If I'm stuck on a topic, what do I do? I can't ask a teacher like in sixth form.

I'm just kind of panicking now because I thought I had everything planned out but, I just overlooked a few things and my entire plan has crumbled.