Taken from aa site
Depending on where it is located, some windscreen damage will result in an MOT failure if not attended to. The screen is divided into two areas for the purposes of the MOT.
The 'A-zone' in front of the driver
- Immediately In front of the driver (The 'A-zone' – a 290mm wide band centered on the steering column and bounded top and bottom by the wiper swept area) – damage larger than 10mm across will normally result in a failure.
- Elsewhere on the windscreen – damage larger than 40mm across will normally result in failure.
Gonna need changing asap though anyway, just because it might pass an MOT doesn't mean it's fine to drive around with it like that
Looks bigger than 40mm.
Try for an acoustic screen when you phone up. They make the interior quieter.
You might have to get Gavin from Autoglass to inject his special resin...