Anyway trying to go through it in order ... Took us 3-4 hours one afternoon.
First step was to remove the carpet in the boot to reach the fuse box. We ended up removing the boot cover, not sure if you can get away with it left in or not. But fairly easy to remove, there are four plugs holding it in place, two at the front and two at the back. Best to unhook it when it is at the back of the boot. You will see in the centre of the plugs a small disk - get your nails around it and pull on it till it pops out. You can them remove the plugs - beware they have a white grease on them that can get everywhere.
Remove the carpet cover over the spare tyre, and just above it you should see two screws or plugs (can't remember) but they pop out easily as well, and I think that there are also two more plugs/screws at the back of the boot, on the edge of the carpet. Once the four plugs/screws are removed you can then remove the base area of the boot carpet and the fuse box will appear!!!
I know the set of instructions I followed said something about removing the fusebox or unscrewing it - we didn't do anything of the sort. You can easily see where the plugs and fuses go - I think it is slot 18 going by the instructions from the BW link.
So once the boot is stripped, next step is to do the same to the car. Without a doubt starting working on the left hand side first as that is the most awkward one!!! Unclip the current door sill, see the photo below of the door step with no sill. The clips are on the inside of the door, and the sill has a small lip that fits round the door step on the outside. So to remove the sill pull it up from inside the door and then move it out from the door step.