Thanks for the helpful replies.
Pip54 - thanks for the tip, I shall PM you for the details, as i'm particularly struggling to get images for the old Inverness distilleries.
jmrl - I've found GW Publishing - looks like they do quite a lot of interesting stuff. Will get in touch with them to see what they have. Cheers!
I also managed to find a series of excellent black and white photos by Professor John R Hume, taken from the 60's onwards. They feature about 80% of the active distilleries of the time, including rarities such as Ladyburn, Millburn, Caledonian, etc.
They're available to view on http://www.rcahms.gov.uk/
for anyone who's interested.