In reply to ebdon:
Without wanting to put a damper on your plans, I'd liken canoeing on big open water like Fionn Loch to mountaineering, in that you need conditions to be really good to risk it, or it can be very dangerous even lethal, and good judgment gained by experience is key. Its certainly not a windy weather alternative, though rain on its own won't affect you much other than making it damper! Wind is your real enemy, and I wouldn't be risking anything above about 12-15 mph as a very rough rule of thumb, maybe less in an inflatable as they tend to be hard work in winds. More than any other activity I've done, paddling relies on good conditions.
On the other hand, your inflatable would allow you to paddle some amazing sheltered and/or small lochs, which might well add a lot to your trip.
Access will be fine, Scotland's good for that sort of thing. Midges will be happy to see you.