If it any help, I had to get a new windscreen done on my truck a few weeks back for it's MOT...
Rang Autoglass, and had a minor coronary after they quoted me damn near £450 for a new screen. RAC AutoWindscreens however were a *lot* cheaper, coming in at £170 all in.
I know it's still not the cheapest thing, but considering the old screen had several repaired chips in it, I didn't mind *too* much, especially considering the old gal flew through the MOT after that.