You fill in a fairly lengthy application form, then get invited to an assessment day, which you attend with up to 10 people. If you pass that, you will be told on the day and then invited to another one-one interview. You have to do a typing test as well (only 35wpm) and a sort of quiz which assesses your personality/decision making. The vetting process usually takes a month, but the interviews are usually quite quick and you'll be told the same day.