Might also be worth trying these folks:
http://www.assaultgliderproject.co.uk/
Booklist from the site -
Silent Ones - WWII Invasion Glider Test & Experiment, (Click on picture for more details)
Arnhem 1944, The Airborne Battle - By Martin Middlebrook - Published by Viking ISBN-0-670-83546-3
It Never Snows in September - Robert J Kershaw - Ian Allen Publishing ISBN 0-7110-2167-8
Arnhem Lift, A Fighting Glider Pilot Remembers - Louis Hagen - Redwood Books, Trowbridge, Wiltshire
Operation Freshman, The Rjukan Heavy Water Raid - Richard Wiggan - Garden City Press ISBN 0-7183-0571-X
Airborne Engineers, The Shiny 9th (9th Field Company RE) - Patrick Pronk - R N Sigmond ISBN 90-804718-3-6
Arnhem - Major General R E Urquhart - Pan Books ISBN 0-330-23273-8
The Cauldron, The story of the Oosterbeek Perimeter - Zeno - Pan Books ISBN 0-330-02089-7
Arnhem Sacrifice - Colin Cummings - Nimbus Publishing ISBN 0-9526619-1-8
Cloud over Arnhem - Kate A Ter Horst - Allan Wingate Publishers
Airborne Carpet, Operation Market Garden - Anthony Farrar-Hockley - McDonald & Co Publishers
A Tour of the Arnhem Battlefields - John Waddy - Pen & Sword Books Ltd ISBN 0-85052-571-3
Silent Invader (Alexander Morrison) - Airlife Classic ISBN 1-84037-368-7
Wot!.. No Engines? (Alan Cooper) - Woodfield Publishing ISBN 1-903953-18-9
Lion With Blue Wings (Ronald Seth) - probably out of print
Horsa Squadron (Will Morrison) - William Kimber, London ISBN 0-7183-0684-8
The Glider Soldiers (Alan Wood) - Spellmount Limited ISBN 0-946771-99-5
Ryan