Not sure what you can get steam train related... some steam railways do annual passes / life-time passes but those will be very expensive.
You mentioned photos - maybe getting a photo of both of them Themed by Enhance Me to a Train Theme (not sure if Victoria has one, send her an e-mail and ask - she may be able to create it for you), then you could use the resulting digital image to make things like a Jigsaw.
As they are train fans... do they have Train Jigsaws of their name. Maybe something to look at.
Also a bit weird: I got a 6 year old a collection of plastic pipes (varying in length from 1/2 metre to 1 metre, and varying in diameter) for use in the bath. Also found a plastic hand pump. These have been a hit with all 3 children in their household who at that time ranged in age from 3 to 8. A small local independent hardware store is where you will find plastic pipes (you will probably need to ask at the desk as they are not a popular item).