Hi there,
I entered the railway as a Guard for a FirstGroup TOC, so I would imagine that the process would be fairly similar to what I had to do. There should be some 'exam' type written tests, which would generally involve:
- ticket related exercises to test mental arithmetic and your ability to check details of tickets (usually two tests)
- a series of passages of text, generally on a safety theme and including mock procedures or instructions, followed by questions on the content of each one
- a test usually involving grids full of different symbols, numbers and letters requiring you to identify and mark certain characters
Be aware that you will intentionally not have time to complete every test in it's entirety; what they are looking for is the answers you submit to be considered and accurate, rather than rushed and messy. Read everything thoroughly - be particularly careful with the ticket tests; there will often be a section where you will have to calculate fares, and this may include being given cards detailing railcards and restrictions, which you will have to include in your workings out. Getting them wrong can cost you the test.
Many assessments will 'release' those candidates who after a certain sections have not met the required standard. If you complete the above tests ok, your next task will usually be an interview of some sort, where you will be asked about your experience and so on, as somebody has mentioned above. Have plenty of answers lined up in your mind, so that you can give examples of teamwork, dealing with problems, giving excellent customer service, etc. You might also benefit from having some decent background knowledge of SR and First, it's aims and how you are 'part of it' all etc, they like that sort of thing
Good luck!