For that number of slides, I would suggest looking at a Braun Multimag SlideScan or Reflecta DigitDia - quite what the relationship between them is, as they look very similar. There is also a similar Pacific Imaging offer, may not be available in UK. No idea on current model or price...
They look rather like a slide projector, but with a scan sensor in place of lens - they take a slide magazine, you set them going, and get on with something else.
An American outfit had an offer - essentially a Kodak Carousel projector, rigging a digital SLR to point down the throat where the lens wasn't - I forget who, or any details - Google will probably find it.
I have read that Nikon Coolscan is highly regarded, but out of production...
For scanning software, I use and would recomend
Vuescan from Hamrick - it will drive most scanners. And in the end, if you really want perfection, you'll end up having to use your favorite image enhancing software (Photoshop or...)
But I would say you are asking in the wrong place: it's a photography, slide scanning project that you're proposing, the fact that it's railway subjects is detail - look for advice in that sort of forum, or on that sort of web site.