I got the stuff and gave it a go, I'm happy to admit it was well beyond my capabilities, patience and equipment.
I did get the trizact to cut through the polished layer of the windscreen.
Its expensive so I only bought 5 pads, which wasnt enough material. Think 20 pads.
I put some spiral scratches on the windscreen too, probably from using the wrong size pads on my DAS at the wrong speed.
So using the correct diameter polishing pad and having some felt polishing pads on hand would be advisable.
The powdered cerium oxide was probably the wrong kind, for tumbling not machine polishing as the consistency was uneven.
It makes an absolute mess so you need an area you can make very messy (I did not) and a ton of well placed and attached drop sheets to keep it off the duco (luckily I did).
So in the end, as I was advised by everyone, a new windscreen was a no brainer.
I would be more confident polishing light scratches, but chips from a screen are probably impossible.
Had I more time I could have persisted but the materials alone would have approached the screen replacement cost!
I would have had as good an experience buying a screen and learning to fit it myself. That's on the cards for next time
So I put all the smileys in to illustrate how I felt about it all
AFAIK there is no smiley for schadenfreude which is probably what
you are feeling reading this post