There’s just a short time left before the October 15th deadline for applications to Cambridge for 2017. Here's the information from the university: http://www.undergraduate.study.cam.ac.uk/applying
And for help in choosing a college, the new Selwyn prospectus is available online: http://www.sel.cam.ac.uk/…/Selwyn_College_Prospectus-2017.p…. There’s also plenty of information on this website: http://www.sel.cam.ac.uk/prospective-students/undergraduate/
Good luck!