May have changed since I did it but FYI your group bourdon will be paper based not on a computer�� Interview will be fairly standard railway stuff tell me about:
Time you have been in an emergency situation
Time you have spent on a training course
Etc etc
If I remember correctly your application from this stage will be 4 parts if successfull at each stage. 1st assessment day will be group bourdon (dots test) on paper not computer based, a fault finding test during which your are given several scenarios and how to prioritise each action accordingly (about 30 questions but don't expect to finish them and your given full instructions to follow). Then a dials test where you have to read several dials and assess which to prioritise and a trainability test which consists of having a set time to memorise a passage and answer questions on it (If it is still the same as our assesment and I beleive it hasn't changed for a while the search for Glop Train on google BIG HINT THAT ONE!!) and that should be your 1st day.
That's how last times went anyway but it was a couple of years back and the format may have changed