where abouts in the south are you? there used to be a place in Alton, Hampshire, that made a lot of the group B rally cars and were exceptional with glass work. Cant remember their name off the top of my head but could probably find it for you (pressuming they are still going!!)
Sorry to have got your hopes up, but the company I was thinking of appear to have gone out of business - shame as they really were top notch. I do have a few friends that have dealings in GF though so will see if I can find an alternative for you!