To answer my own question at the top of page 2, paid £640 last week for both front and rear discs and pads at the local franchised VW dealer (Inchcape).
Tried booking via the website first and they wanted approx £1k. So rang them up and asked for a quote over the phone and was told £640.
I'm not saying there won't be cheaper garages out there, but this was the best I could do for genuine VW parts.