We did it early october a couple of years ago. Best hols I'd had in ages; we keep on saying we should do it again. It wasn't cheap! We spent two weeks doing it and must have spent 3K on board and food. The good hotels are not cheap up there. October is a good month because the roads are mostly empty and also very few 'white goods on wheels' (camper vans) around. There's nothing worse that being stuck behind a huge camper-van on a single track road. You're trying to see the country side and all you can see is a slab of white plastic in front of you. On the bad side a lot of the tourist spots are closed but we went mainly for the driving and quiet country side. Lots of otters and seals :-)