There is a recent book by Osprey that, while not as detailed as the other books mentioned here, does give a nice capsule history of the unit and has some good illustrations.
FIRST SPECIAL SERVICE FORCE 1942-44, published in the ELITE series.
http://www.amazon.com/First-Special-Service-Force-1942/dp/1841769681/ref=sr_1_1?ie=UTF8&s=books&qid=1246365579&sr=8-1
Twelve bucks at amazon - I have a copy, and I liked it. Again, about half the book is devoted to "buttons and bows" but there are some interesting photos (nothing particularly rare) and the colour plates are all original and well done. Osprey used to get a really bad rap, and deservedly so, but in recent years I think as turned things around and is producing a much higher quality product than it did 20 years ago, in terms of research and getting basic facts and details right. I can't speak to the accuracy of the book but it seems like a good primer or general source of info.