You need to clear the interview first, followed by a contract teaching (6 months or 1 year depending on when you get in) before they deem you suitable to enter the teacher training course (called PGDE).

I didn't clear the interview stage. And yes supply is more than demand these days, especially with the low birth rates and school mergers. Hence to even clear the first stage you need to be the best of the best, as the vacancies available is very little compared to last time.