When an 'experienced' driver (i.e. with more than two years experience) commits a driving offence which would bring the number of points on his licence to 12 or more, he is not offered the opportunity to pay a fixed penalty. He must appear before a court. This is because only a court is empowered to disqualify an 'experienced' driver.
However, the Road Traffic ( New Drivers) Act 1995, requires the DVLA (rather than a court) to revoke the licence of any 'probationary' driver who reaches 6 points on his licence. It seems, therefore, that an actual court appearance would not be necessary. (Note that DVLA have no discretion. They must revoke the licence. A driver can appeal against the driving convictions but he can't appeal against the decision to revoke his licence).
The driver can only get his full licence back by passing another driving test. (This can be in any class of vehicle for which his original licence was valid). Note that the driver isn't officially 'disqualified' from driving. If he was, he wouldn't be allowed to apply for a new, provisional licence to enable him to practice for his test. To obtain a provisional licence, the driver should complete form D1 and provide the relevant ID, photo and fee, just as he did when he first started driving.
Source:
http://www.dvla.gov.uk/drivers/endorsem.htm
(See Section 6)
Chris