Assuming windscreen cover is on the insurance, then a minor chip 'incident' would ensure a relatively cheap replacement
The windscreen on my 15 year old camper van has got signs of delamination on the black outer edge and has sailed thru every MOT with no mention of it, so I guess it would have to be pretty bad to be deemed a failure.
MOT handbook makes no mention of delamination:
http://www.motester.co.uk/mot-checks...-of-windscreen