To apply for university you must submit a UCAS application form. That's assessed by university admissions staff - we'll call them 'the Admissions Tutor'. If what the Admissions Tutor sees on your form is convincing you'll get an offer, otherwise you will be rejected - end of story. This article will help you put together an outstanding UCAS form.
What goes onto the UCAS form is VITAL, and this 'Six Top Tips for an outstanding UCAS form' article is to help you make it the best you can. The UCAS website has plenty of information about the practicalities of applying. Click on the + to expand the section you want to read.