Here is the Calmac Timetable for your route. Quite often you can turn up and go on a lot of the crossings, and Scotland is normally only really busy in late July / August. However, I should give Calmac a call - they are very helpful and friendly. You can navigate to the contact page from the links at the top of the timetable.
Philip
<<Calmac Mallaig - Armadale>>
Philip
<<Calmac Mallaig - Armadale>>