To add on to what Echo2707 said, if you don't get the results you want, gap years. Gap years are an amazing thing. No university or other education for an entire school year, plus you get to use your final A-Level results. If you aren't pleased with your Y12 results, take a gap year and apply with your actual results because you'll probably be able to get into more places and you'll probably have a lot more fun than going straight from revision to university life.