Although not 15" gauge, some might find this interesting.
Yesterday I took the family down to the Almond Valley Light Railway in Livingston.
The railway is part of a larger site which includes a Shale Oil museum with a loco and a few wagons, childrens play areas with trampolines and go carts, farm animals and a preserved mill.
The railway itself was built as part of the site using mainly ex MoD stock and track although the main loco in use is ex ICI/Nobel explosives. Gauge is 2'6" and the main station would make a nice little layout. The line runs for 500m to a second station consisting of a platform and a run-around loop.
I've uploaded some photos of the station, stock and shale oil museum to photobucket here : http://s1151.photobucket.com/user/backwaterscotland/library/Almond%20Valley%20Light%20Railway
There's more details on the stock on their website here : http://www.almondvalley.co.uk/Railway.html