As part of your application, they ask you your course preferences (location and format).
If you are successful in your audition, they will then offer you a course. For example: 2 week course in Leeds during August, online course, weekend course in London in the Autumn. The usually prioritise your choice of location first.
You then have the choice of accepting the course they offer. If you want a different course, you can decline the one they offer you but then you go onto a waitlist for the one you prefer. I believe NYT has very little waitlist movement, so it is a big risk and if you don't make it you will need to reaudition the following year.
My daughter auditioned for the first time last year. She wanted the London course in August but was offered London, weekends in January and February. It's been full on but she took it as she did not want to risk missing becoming a member.
NYT has a phenomenal reputation in the industry, so if you're interested in a potential future in it, I'd highly recommend going for it.
Good luck!