If you are looking for additional material then this is a small list:
Avionics Fundamentals
United Airlines
ISBN 0 89100 293 6
(gives some good descriptions of navids like VOR and NDB. Also got some Logic stuff in it)
Handling the Big Jets 3rd Edition
DP Davies
ISBN 1 56027 071 3
(very useful after all these years. Probably not so useful for the JAR exams but gives a good insight into the differences between operating a light piston and a heavy jet. Also a must when you start going for jet interviews)
Aircraft Instruments and Integrated Systems
EHJ Pallet
ISBN 0 582 08627 2
32.50 quid
(Very useful book. Can be a tad "heavy" but pretty good for IRS/INS/autopilots etc. Explains basic principles of nav, gyro's etc too)
A&P Mechanics
FAA
Powerplant ISBN 0 89100 079 8
Airframe ISBN 0 89100 080 1
General ISBN 0 89100 078 X
(Brillliant series of books. Designed for an maintenance engineer so pics are detailed. Goes through pistons/super/turbo charging, fire and ice protection, propellers, electrical, hydraulic systems. Even touches on turbines. Need to bought as the series though.
Pilot warehouse has them)
The Jet Engine
Rolls Royce
ISBN 0902121 2 35
(brilliant book. A must for all aspiring turbine operators.)
Aircraft Performance Theory for Pilots
Pete Swatton
24.95 quid.
(invaluable for PoF, Perf and M&B Jar)
Dictionary of Aeronautical Terms
Dale Crane
ISBN 1 56027 071 3
(invaluable - every one needs this book)
Meteorology for Pilots
Mike Wickson
ISBN 1 84037 284 2
25 quid.
(Great for climatology)
Radio Telephony
CAP 413
CAA
Visual Aids Handbook
CAP 637
CAA
Human Factors for Pilots
Green Et al
ISBN 0 291 39827 8
18 quid
(good book for JAR)
Aviation Law for Pilots
Underdown and Palmer
ISBN 0 632 05335 6
28.50 quid
(pretty good for JAR OPS)
Mechanics of Flight by Kermode 24.50 quid.
Radio Aids by Underdown and Cockburn
ISBN 0 632 05573 1
Navigation 6th Edition by Underdown and Palmer
ISBN 0 632 05333 X
Aircraft Flight by RH Barnard and DR Philpott
ISBN 0 582 23656 8
Also, check out the Mike Burton series of books.
Review the Trevor Thom' books too you may have used for your PPL.
For Humour 'cos you'll need a laugh.
Bluff your way on the Flight Deck
Capt Ken Beere
ISBN 1 85304 373 7
2.99 quid
What goes up Might come down by David Gunston
(Very very funny ATCO)
on CD and tape
12.50 quid.