I like the SAS very much.
For a dated 1980s movie that is still pretty good, check out “Final Option”, the star was a reservist SAS according to an SOF article of the time, being known stopped his options with the SAS. http://www.imdb.com/title/tt0083941/
The SAS used to be surprised at how our Special ops personnel, (not Delta of course) could wear t-shirts and uniforms of their type units and openly let it be known that they were special ops, Rangers, SEALs, Green Berets etc, they weren’t allowed to do that.
For a very good, but low keyed movie (the kind I like) try the movie that does a good job of following the book “Bravo two zero”.
http://en.wikipedia.org/wiki/Bravo_Two_Zero