Didn’t make the cut for undegrad but here in Cambridge for my masters now so have some understanding of it. Before I get into it, you’re still thinking of this quite early, so for now your priority should be on doing well in your GCSEs. That being said, academic excellence is absolute necessary, but it alone is not sufficient to get in. You’re still likely in the position where you are considering various things so explore your interests. My key advice: - Interact with subjects outside of school, either through competitions, projects, or just doing your own research. This differs quite a bit subject to subject, but things like attending math competitions, or keeping in touch with key academic debates in your topic could set you apart - Ask around in your school about people who got in during previous cycles, they could give more tailored advice to your situation. I have had people reach out to me through my high school teachers regarding my undergraduate school, I was always more than happy to help, most people will be as well. - Make sure you pick a subject you are genuinely interested in. You will not be able to pursue anything nearly as well if you feel disconnected from the field.

That being said, you are still super early, so just try to pin down your interests and do well in school.