In reply to Rigid Raider:
Head torch
Kitbag (better than rucksack as can be stowed/ rolled up more easily)
Gloves. Having sailed around Scotland and further north for nearly 40 years, I don't agree that sailing gloves are essential. However, I do think robust rubber gloves are excellent. Marigold industrial ones in particular. Get a size a wee bit too big and they'll be great with power stretch liners. I prefer to keep my hands warm and then use bare hands for rope work. Helming can be done with gloves on.
Take good warm hats (what you'd use for winter hillwalking)
Boots. Sailing specific rubber boots maybe useful, but on a 22" boat you won't have lots of deck work. You'll be fine with normal-soled rubber boots.
Sunscreen - you can burn easily off the west of Scotland.
Have fun! Those bays along the SE (distillery) coast of Islay are stunning anchorages - don't miss the Ardmore islands!
Post edited at 13:48