One of the stations (and villages) I love to visit up north is Helmsdale, I've seen so many old pics of steam and also BRCW diesel days, reading some articles today has made me think this could be modelled convincingly in a 3'6 to 4 ft diameter circular layout, you can tell I've been reading the RM article about the 2FS Woodhead route!

Helmsdale has the advantage of being situated on a fairly tight curve anyway, and also has prototypical scenic breaks.