They ask you to write online application. It is followed by a compatibility test, just remember that during this test, health & safety is their priority.
You then have to undertake a video interview (Questions are below).
If you are successful, you are invited to an assessment centre (usually in Milton Keynes). This day comprises of a 5 minute presentation on something you're passionate about (but topic may vary every year). Then you are interviewed by at least one person, you may get two interviewers. Then you have a group task.