Applying will get you a telephone interview, which is a short discussion which will extrapolate on your application. Assessment centres involve a 2 day process. Starts with 3 group exercises focusing on your abilities to communicate effectively with a group, moving on to a mathematical ability test. Then dinner enables "networking" with current graduates. The next day starts with being told if you were to be interviewed or not. If you reach the interview, this is minor technical focus, and mostly is dressed formal, with an informal feel to the discussion. It only took 5 days after this to be offered a job, so things move quickly.