Just to conclude my rain shower issues;
I read the sticky on water ingress, contacted Volvo customer support head office, had it confirmed that my local dealer would know all about the FOC re-bond repair and promptly called my dealer for an appointment.
As expected, my dealer was not aware of the FOC repair :-(
After a few calls between us they finally had the confirmation that they were able to do it FOC and I dropped it off last week. When it arrived they said the paperwork only allowed them to do S80 windscreens
A few more phone calls between the dealer and their head office and finally it was all sorted.
The original Volvo screen was removed and re-bonded, no leaks (so far).
So in summary: It was a fair bit of hassle, and two trips to the dealer, but all is well and I can't really complain.
So a MASSIVE thank you to this forum for the advice and information that allowed me to get it fixed free :-)