From my bookshelves I can suggest ….
Haynes "Enthusiasts Manual" for the Military L/R from 1948 on, so Series 1 to Defender, 80-110" models.
Veloce publishing do a book on the Half Ton Military L/R ie: the SWB 88 models, std and air portable Lightweight.
Martin Hodder has 'Land Rover, Simply the best' published by Haynes.
Bob Morrison has 'Combat Land Rovers Portfolio #1' published by Brooklands Books.
James Taylor has 'Land Rover Military one-tonne' by crowd press. ie: the 101" forward control models.
Veloce have printed a book called "Land Rover SIII Reborn", which follows the strip down and rebuild of a civilian 109. - the current Revell model in 1/24th.
Extreme Landrover Discovery by Haynes has plenty of photos of Hi-lift jacks, sump plates, roof racks, bull bars and many extras to let you scratch build these sort of extras for any model.
Decide what you want to start with, civil, military , Police, Paris Dakar, and don't forget the Australian Perentie 6x6 versions, Belgian Minerva or Spanish Santana, which were built under licence, and type that and L/R into google. There are literally hundreds of books on the subject. Some are marque histories, others development histories of a specific model such as the SII or the Defender.
Sometimes a coffee table picture book is just as useful as full on technical manuals. There are also 2-3 L/R magazines in the UK, buy these if you see anything that takes your fancy, and they will also have recommendations on books.
Hope this helps.