The driving ban would start at the time of sentencing so if he appeared in court in March 2008 and received a 3 year driving disqualification, then the ban would expire in March 2011. This is when he would be able to apply for his provisional licence. The penalty points would stay on his licence for 11 years which means that when he gets his full driving licence, it would be endorsed with the points and the offence he committed.
This has been speculated on the assumption that the worst of the 2 offence (drink driving/driving without licence) is drink driving. You should contact the DVLA or court where your son was sentenced to confirm though.
