How to learn new things without going to college.

What do you mean how would you learn these topics? If you know what topics you need to learn, go and revise them. I'd think that if you didn't go college then you'd have it all under control and planned. If you can't self teach yourself then college is the only option.

I am trying prepare for my BTEC Exam I have 6 months to revise I have done a mock paper but I can see what topics I need to improve on.

How would I learn these topics without having a tutor teach me it?

Are you going to be completing the course with a college eventually (and this is just to get ahead) or are you fully self teaching?

I will be going to college in September but want to get ahead so I can pass with a certain grade

If you've done past papers to identify weak areas, use resources (internet/books/videos) to try and get your head around the content. Even if it means you're just familiar with it, it will help when your college go through the material

Yep and if anyone is stuck I can help them too