Hi Simon, I had the same issue on my 55 plate GTI, didnt realise until i was told on my service at VW, that particular garage said that it needed the spoiler to come off as the screws were on the inside which meant the need for a body shop! i was shocked when i heard that and somehow it didnt fail the MOT on it.
so i called a bigger VW garage and they said £156.82!! i asked about the need for a body shop, they said it doesnt have to be, you can actually bond it on, so i had it done and it works fine!
im sure there was a previous post about the high level brake light here and some guys managed to do it themselves
hope that helps
Ken