At this point I am going to leave the fuse box for now and move onto routing the cable from beside the rear-view mirror. This is a lot easier that it seems. Slowly lift the top edge of the A pillar cover trim (arrowed).
As it comes away along its length pull outwards directly towards the driver’s side A pillar. Remember those plastic clips! We do not want to be pulling sideways against them. There is a clip at the top and another at the bottom of the trim. You can see the square hole where the clip locates.
I have a speaker in my A pillar cover trim and I could not work out how to unclip the wired connector to it so I played safe and left it alone. The cover can be laid gently at an angle across the dashboard.