The decision about driving gets referred to the DVLA, who make a decision based on the doctor's advice. Last time my dad had a seizure he was banned from driving for a year; he reckons it'll probably be the same this time. Two of the things in 15 years (or thereabouts, I can't remember exactly when the last one was) is a pretty low hit rate, but it also means it's unpredictable -- it's not frequent enough to establish a pattern really.