I didn't necessarily need to take it out tbh, but for the sake of a few more screws, it gave me more headroom and saved from a few more sraped knuckles!
So all the wiring is in, ready for the lights to go in!
Finally managed to get hooked up to vids to find out my soft wear, and it's running 0651, so happy days me thinks!
Still unsure about messing with byte 18 though. Keep googling it and seeing what other people have coded to, but not many are UK cars, and not seen any that are led rears + xenons + LED drls! :/