Auto fluid should be changed at 60k by which time its well burnt!! Service intervals for this should be much sooner than what LR states.
Floppy is right in saying you have to use T4 but you can guess it and get it pretty much spot on. A little over or under filled wont harm it.
The drain plug is the big (24mm if i remember correctly) bolt on the bottom of the gearbox.
Filling port is on the front of the box on the top of the valve block cover, its got a rubber bung in it.
The level plug is on the bottom of the gearbox next to the selector cable, depending on what year your car is, it'll be either a 5mm allen key or a 14mm bolt.
ATF temp has to be around 80 degrees to check the level with the car on a level surface, engine running, in neutral.