Hoo, I don't know if your still looking for books on this subject or not. I've recently acquired 'Coastal Forces Vessels of the Royal Navy From 1865' by M.P. Cocker, published by Tempus, 2006, ISBN 0-7524-3862-X.
It's a general overview of all coastal vessels of the RN up to around 2004. It features brief specs and some good photos and layout plans of diverse types such as Monitors, torpedo boats, MTBs, River Gunboats, Landing Craft, Hovercraft etc.
As a starting point its ok, the specs etc. are brief but it gives entire class numbers and builders etc. and is a good starting point, but just don't expect a nut 'n' bolts approach within 256 pages. It tries to record all known losses though so has some value in that regard. Overall a good starter read. 7 out of 10.