Here is a step-by-step guide on how to do this. If doing this for the first time, allow about half an hour. After that it is about 15mins to remove the floorpan.
Slide the drivers seat fully back and undo/remove the two bolts at the front:

Now slide the drivers seat fully forward and undo/remove the two bolts at the back. You can now remove the drivers seat from the vehicle:

Fold back the carpet behind the drivers seat and undo and remove the wing bolt holding down the rear access cover and remove the access cover itself:

Now undo/remove all the bolts holding down the floorpan (red circles) and fold back all the cable clips (green circles). The top right red circle is a cross head screw set inside a rubber bump-stop - remove this as well. The top left bolt is tucked under the passenger seat floorpan and is a little more awkward to access/remove.

Undo and remove the two cross head screws holding the handbrake cover on. Lift off and remove the handbrake cover.

Undo and remove the lock nut and adjusting nut on the handbrake cable:

Lever out the handbrake cable from the handbrake assembly:

Undo and remove the two cross head screws that hold down the fuel flap release handle:

Twist and lift out the nipple on the fuel flap release cable (can be a bit tricky/fiddly to work out the first time!) Now push the nipple through the fuel flap release handle and remove the handle

Push the fuel flap release cable through the grommet in the floorpan:

Push the handbrake cable through the grommet in the floorpan (green circle) and undo the handbrake cable switch wire (blue circles). Make sure that the main wiring loom is clear of the floorpan and now lift the whole floorpan clear and remove from the vehicle:

You now have much greater access to the engine bay/turbo/egr etc....

Refitting is pretty much the reverse of the removal procedure, but do make sure that the handbrake cable is tightened properly and the locknut fitted.
Apologies for the condition/state of the interior, but I used the Mud Monkey (AKA mucky work van!) as a demonstrator because I needed to remove the floorpan anyway....