This book from which the famous film was taken, is well worth a read in it's own right. It is different from the film in a number of ways, there are two islands not one and unlike the film there are Catholics as well as Calvinists on the island. Also the girl courted by George Campbell (played by Gordon Jackson in the film) is not the sister of the girl courted by the English soldier.
If you enjoyed film, which I believe is a masterpiece, then read the book for a more complex and detailed, but just as funny, version of the same story.
There are also a number of lesser known books in MacKenzie's Highlands series, such as Rockets Galore, The Rival Monster and the Monarch of the Glenn, which has nothing to do with the TV series except that it is set in the Highlands and has the same title. Most are out of print but all are worth the efford to find and read.