Strangely, royster3k, he may well be locked up, but ironically not for a motoring offence. There are very few purely motoring offences for which you can be imprisoned. The only ones I can immediately recall are Causing Death by Dangerous Driving, Dangerous Driving, Driving Whilst Disqualified, Excess Alcohol (and the associated offence of Refusal to supply a specimen), and Failing to Stop/Report an accident. No others are deemed worth of a custodial sentence no matter how many times you commit them.
There have been recent instances of people with a predilection to continually commit motoring offences to be served with an Anti Social Behaviour Order (ASBO) in an effort to prevent their re-offending. Breach of an ASBO carries a five year maximum prison sentence. If worried_gf�s boyfriend is not imprisoned on this occasion for Attempting to Pervert the Course of Justice it seems only a matter of time before he is convicted of another offence warranting custody (most probably driving whilst disqualified).
Magistrates (and of course judges) do have the right to impose driving bans for any offence, not only those related to driving, if it can be shown to be proportional and relevant. (A burglar can be disqualified from driving if it is considered that driving assists him in his activities). There is no limit in either court to the length of those bans, but lengthy bans (say more than 5 years) are seldom imposed and life bans very rarely. The thinking behind this is rather along the lines you summise. It is thought that the miscreant, with little or no light at the end of the tunnel, will be tempted to drive anyway. (I�m only telling you how it is � I don�t necessarily agree with it !!!).
There is certainly a case for increased penalties for drivers who commit serious offences or a string of minor ones. Unfortunately this is not likely at the moment.