We had a guy called Matt Vinney do ours. Worked for Sheffield Window Center for 20 years and went independent 3 years ago. He did ours and some windows upstairs. Top job, Same glass as the main sheff companies (i.e from Central Glass) but about 60% cheaper.
Does it himself as well rather than the usual monkeys that come round once you've had a quote.
His mobile is 07932 022997, but he has a website as well I think.
My personal take on the material, we had wooden frames in our house, they had all rotted and flaked so now we have PVC, and they look fine.