OPERATORS: On the Streets with Britain's Most Secret Service (Pen & Sword Military Classics) (Paperback)
by James Rennie

I have skimmed this and thought it was interesting but its basically more on the training and selection program by a former member of the 14nth Intel Company.


Big Boys' Rules: The Sas and the Secret Struggle Against the IRA (Paperback)
by Mark Urban

I liked this book. It's more of an overview about the various units and has some TTP/lessons learned material that I found relevant. It's my favorite of all of these books.

SHE WHO DARED: Covert Operations in Northern Ireland with the SAS (Hardcover)
by Jackie George (Author)

This also covers the author's experiences of selection and training for the unit. Very little on TTPs and actual operations.

I'm sure you are already aware of the book, Immediate Action, by Andy Mcnabb. It also had some information on their operations.