On US left hand drive vehicles, the amp is located under the passenger seat. There are four plastic covers that need to be removed first, one on each corner of the seat. They are held in place by plastic tabs that are reinforced with metal clips. You can pull them out by hand, but a flathead screwdriver can make it easier to get some leverage. Locate the tabs first to see which direction you need to pull in order to get the plastic covers off. Once the covers are off you will need a size 55 torx bit to undo the screws holding down the seat. There will be two screws in the front and three in the back. Moving the seats forward or back helps in accessing the screws. These pictures are from the driver's side.
Under the front of the seat you will see a small black plastic box that says Ford. There is a 7mm screw that needs to be loosened and then the box can be pulled off. The box has the connectors that supply power to the seat motor.
Some of the wiring is attached to the seat by plastic clips that will need to be undone. Again, a flathead screwdriver will come in handy for leveraging the plastic bits out of their holes. At this point the seat can be removed. Rather than trying to take the seat out the front door, I found it easier to push the front seat back and rest it on the folded 2nd row seats.
Hope this helps.