Good luck with it, I'm looking to do a journalism course and go into journalism/photojournalism myself - so I understand where you're coming from. I could see a study of a 'spotter being interesting and getting some different shots at the end of it.
What you may or may not realise is that there's quite a few young people on this forum, some of whom may be slightly suspicious that someone wants to take the p*ss out of them or make them out to be something they're not. Of course, some are also suspicious of a stranger with a camera asking if they can meet them - it can sound dodgy from some perspectives, but I fail to see how else you could do it.
Also, about the nicknames, quite a few here are rail staff and/or would rather prefer to have some anonymity in case their employer/friends come across what they've said - the consequences range from being labelled a "trainspotter" to disciplinary action.
Hopefully this, erm, essay will help you with your project as well as help you understand the viewpoint of many members here (not that I speak on their behalf, or the forum etc.)
Angus