Good luck with this Jamie, I shall be following the build with interest. Green Ayre was my local station, and I bunked the shed several times. I didn't know it was called bunking in those days, just mooching around when we were kids. The first loco number I collected was 46410 on Green Ayre shed, that must have been about 1955. I suppose you have seen the usual railway books for the area? Railways around Lancaster,by Ken Nuttal, and Ron Herbert's book The Working Railway. Also Binns' Little North Western Railway has a few old photos. The Rev Bob Jackson produced a book about the electrified L-M-H lines but I never bought a copy.
The shed is under Sainsbury's now and Greyhound bridge is a road bridge and much changed. IIRC the hand crane on the grassed area where the station stood came from Hornby. Great name eh? It cost one old penny to ride from Green Ayre to Castle station, passing the engine shed. Some of the windows in the later units were frosted, which made it difficult to see out. If you were lucky the ticket collector wouldn't bother you and it was possible to go back and forwards all afternoon for a penny. Pleasures were a lot simpler in those days. The coal merchant in the station yard was, I think, Laycock. They may have had their own POW coal wagons. There was a wooden wagon in their livery at Steamtown at one time, painted grey or blue with white lettering.
Green Ayre shed was very compact, cramped even, with access to the shed via the turntable. I often thought it would make a good model.
Geoff.