Ratty you have provided no location. We have no clue what continent you are on. I took the time to look up the owners manual online for a 2007 diesel RHD and the manual shows it under the left seat. Did you raise the seat? What is under there? Did you look under the right seat? With market differences it may be under the other seat.
This is why we ask for Rover info in your signature and a real location in your profile.
You seriously need to start looking up things on TOPIx in the owners manual or purchase an owners manual set off ebay. You also still need to add your Rover info to your signature as noted above and in the guidelines.
The very first thing in the owners manual...
Note: It is necessary to raise the left-hand seat to its highest setting and then power the seat forward to its foremost position, before accessing the navigation DVD unit.
1. Turn the starter switch to position I, then move the lock/unlock button on the front of the DVD unit to the unlock position.2. If a DVD is already loaded, push the eject button.3. Load the Navigation DVD with the printed side upwards.Caution: Do not allow moisture or foreign objects to enter the slot.4. Move the lock/unlock button to the lock position.