"The points remain valid for 3 years from the date of conviction but you are not subject to any further probationary period or terms as a new driver. If you reach 12 points within any 3 year period, you would be subject to a totting up disqualification, as would any other driver."
So youd be banned
http://www.drivingban.co.uk/drivingban/driving bannewdrivers.htm
you wont be able to just take test again. Even if you could afford to insure a car with 12 points you would be banned from driving it.