So, sorted this today, simple job really. Only the two wires going into the fuse box are the problem, the wire from the alternator is long enough anyway.
I'll try to give a quick step by step on the other two.
Unclip them from the red battery terminal block.
Take the lid off the fuse box, you will see three separate rows of relays/fuses. Unclip them from the box and lift them up and out the way. start with the one nearest the wing, you will need to undo the 12mm nut in the corner and take the wire off.
You will see those two wires connect to the two larger boards, and they are also both connected inside the box anyway!? Pull the wires back into the box area, the plugs won't fit through the hole so you need to open up the flap, get a screwdriver in there and pry it open.
Get a nice big drill and put a hole in the bottom of the box, underneath where the wires connect to the boards. Feed the plugs back through there, plug them back into the battery terminal , clip the fuse box back together. You now have quite a bit more length and should have no problem connecting the battery even with the terminals on the far side.