Thanks, Ernie, i've just ordered some! With the assistance of Vol. 1 of Patrick O'Sullivan's history of the Valentia line, in which he has drawings (to what looks like 2mm scale) of Cahirciveen and Mountain Stage stations, I'm doing a drawing at the moment of something roughly in between the two in size.
Mine will have what will look like a felt-surfaced roof, as some such buildings had. While many corrugated iron buildings had (have) roofs of the same material, I just thought it would look a bit like overkill on the model. There will be corrugated-sided goods shed also!