Just had a look on the MOT testers guide/website as posted in the FAQ section and couldn't find an answer. I never remember the operation of the front windows being checked in any of my previous MOT's

Found my answer to this now and no they don't. So one piece fixed position front windows on a mk3 is a posibility

That's not true. You must have an aperture in the front window, whether that be the window itself or a hole or sliding panel in the window.

Are they road legal?

We have asked a number of MOT stations whether Perspex windows are road legal and the answer has been “yes” as long as they are not solidly fixed, or if they are that they have an opening aperture in them.

As most of the rally cars in the UK have to have a valid MOT certificate, the argument would be the fact that there are thousands of cars fitted with Perspex windows that are road legal in the UK.

Taken from http://www.plastics4performance.co.uk/faq.asp

I'm currently working on some one-piece polycarbonate front windows which should hopefully go down all the way, using Mk2 golf mirrors as they have a bigger baseplate.

we run 2 or 3 cars with solid perspex windows and no sliders which are bolted solidly into the frames and have had no problems with MOTs

Yeah, you'll probably get away with it, but that doesn't necessarily mean it's legal.

yea, good job really!

as how many mk4 polos would fail, the windows always bloody break