'A car windscreen will not pass the MOT if it has damage that is more than a 1Omm circle in the area swept by the wipers and 290min wide immediately in front of the steering wheel. It can also fail if the damage extends beyond a 40mm circle in the rest of the area swept by the windscreen wipers'
A 10 cm circle is about a 1p piece.
However, you say a hole, which if true may be more severely considered than damage. Is it a bullet hole?
Spot on Panic button , It may be repairable , get in touch with your local Windscreen fitting centre and let them have a look at it , some are repairable depending on size and type of damage , Don't expect dissapearing miracles though , they are not Paul Daniels ....
IF you are Fully comprehensive it could also be free!!!