as ian mac says.....
also note the increasing scale of 6, then 12months then 2 years for totting up only applies if you get back upto 12 points within 3 years of your last totting up ban.
so you could get a totting up ban every 5 years and each time it should be a 6 month ban.
however with all serious driving offences, the magistrate can always be a cunt and ignore the guidelines and give out a stiffer penalty within the range he is allowed to hand down. The magistrate just has to justify it.