I had the same, called insurance company and they said they would have a guy out to my job the next day.
I then told her I had (like most of you) about 50 tiny and I mean tiny little pebble marks. You wouldn't even call them scratches but she insisted that I now get a new windscreen which was completely covered and didn't affect my premium!
This actually suited me and was a blessing in disguise as my windscreen was scratched badly a few months back. Just call them up to make sure and in the meantime try get your hands on one of those stickers you put over the crack to stop it spreading!