Yo victoria, welcome to the forum.
You'd be surprised what a great source of railway photos eBay is. I keep finding some absolutely unique gems on my pet railway subject (and I won't say what it is
).
Make sure your search criteria is finely tuned to reject the nonsense, but let the possibles through.
(I used to drive out of the Southeastern side of Vic, so I know where you're coming from. Some fantastic traction to be seen from Nine Elms and Stewarts Lane).
Best wishes,
FP