Hi Anthony,
This build is an absolute pleasure to follow. By way of a quick introduction, some years ago I also intended to embark on modelling the Highland Railway in 2mm Finescale. Unfortunately I took a long break from modelling and never progressed beyond accumulating a range of half-finished etchings. I recall that there were a few of us interested at the time, so Allen Doherty of Worsley Works and the late Andy Copp of Lochgorm Kits kindly produced a few scratch-aid etchings, including of course the 8-wheel tender Barney.
I am gradually getting back into the hobby and looking at picking this up again. However, with my modelling skills now extremely rusty, it will take me a while to build up to any serious progress. I have even considered starting off with some N Gauge "bodging" whilst I work on my 2mm skills, although this is shameful impatience! In the meantime, I will be following your progress with delight.
Best wishes,
Jamie