Chances and guidance to the best university?

I am a year nine student at Walbottle Campus Technology college, not the best school but is able to give me a decent education. I am aware that it is a while before I start university but I thought it would be to my advantage if I get a head start. My family is not rich and my school is not private. I just live life like most people in the United Kingdom. In years to come I would like to apply for top universities such as Ox-bridge. I am also aware that I should not only apply for these specific universities as the chances of me being accepted into such an academic university is minuscule for a middle cl citizen like me, therefore this is the reason I am asking for this advice. I would prefer to be given advice on how to have a better chance of getting accepted into a red brick university but information on other universities is needed non the less. Thank you for reading and I hope some help will be obliged. :)