I applied online and you have to fill a form out about yourself and then you get asked a series of questions, some of which are customer service ones, maths and english.
A few weeks later I had a call from a lady saying I passed that stage and she was inviting me to a group selection interview. In this I was in a group of 6 people, they have you fill a form about your self, have you work in teams and try sell a product and while this is happening you have a main person letting you what you need to do and then you have 3 other people watching you.
If you're successful they invite you back for a 1 to 1 interview with your manager. S/he will take you to the shop floor show you around your department ask a few question then if you're once again successful they offer you the job. I was hired as a christmas temp but was kept on and still working there today.