Applying to university is a long and complicated process. You need to get it right so that you end up in the right place.
You need to start at least a year beforehand, but if you're thinking about applying somewhere really competitive—say, Oxford, Cambridge, or a course in medicine—you need to start much, much earlier so that your UCAS application and your personal statement look impressive. Let's assume that you've done that bit, and that you've got all the work experience and all the different bits you’ll need for your personal statement.
It's summertime, and school has broken up, so what I want you to do is start thinking about your university choices. Start doing a bit of research into courses and universities, and start thinking about your personal statement. The best place to start is by making a big, broad list of things about you. Don't start writing it yet, but start thinking about what sort of things you could put in there. Loads of university open days happen in June/July, so it’s a great idea to go and visit the places you’re interested in to see what it feels like to be there. Do you get a good feeling when you're there, or is the feeling not so great? University applications open early September, but universities do not wait around until the deadlines to start handing out places.
Remember, the earlier you apply the better, so the more organized you are, the sooner you can get your application in. That's why it's terrific to have spent the summer thinking about what course you want to pursue and which university you want to attend. All of this will help you craft a polished personal statement. You also need to start nagging your referees—and I mean gently nagging, of course! You don't want to bother them too much, but your application can't be submitted until your referees have added their reference. So even if you're super organized, and you've written your personal statement, and you're ready to go at the beginning of September, your referee may not be. That's why it is a bad idea to leave your application until right before the deadline. If you tell your teacher the day before the deadline that you want to apply to Oxford, they will have to write a reference quickly, and they may not do an outstanding job if they don't have much time. They may not even get it done at all!
The deadline for Oxford, Cambridge, Medicine, Veterinary, Dentistry is mid-October. That's mid-October the year before you start. The deadline for the rest of the courses is going to be mid-January, which is the same year that you start. If you get rejected by all five places, you can add some more on in about mid-February. Art and Design courses have slightly different deadlines, which tend to be around mid-March.
After you've received all of your five decisions, you have roughly a month to decide which one you're going to accept as your firm and which one is going to be your insurance choice. For example, if you have them all by the end of March, then you have to make your decision by the beginning of May. If you have them all by the end of May, you have to make your decision by the beginning of July.
In July, Clearing is going to open. If you don't have any offers and you didn't want to put any more on, then you can apply through Clearing. If you didn't apply at all the first time around, then you can also apply through Clearing. This is where the universities open up any remaining unfilled slots they have in their courses. In mid-August, we get to A-Level results day, and this is when Adjustment places open. If you did better than expected, you could apply for an Adjustment place, or if you did worse than expected, you might have to go through the Clearing system.