Maybe just start reading a few books into several topics you like? I'm considering English Literature and potentially combining that with French, so I'm reading a lot of fiction for English, I need to get started on reading more French (I've watched a film or two and made friends with a French girl online, kind of like pen-pals) and I'm also considering something law-based or political, so I'm considering getting some reading for that too. I'm also doing essay competitions, planning to apply to summer schools when they open in January, etc.
(I'm also in Year 12)