IIRC, the workshop was about three hours, but it was surprisingly useful. The instructors treated you like adults and not children or criminals, and they gave fairly useful tips on driving and looking out for things like lights suddenly changing, ensuring you are in the right gear, how you're supposed to react if an emergency vehicle wants you to go forward when you're by a set of traffic lights with a camera, etc.
However, on the drink driving front, given the news with Ant from Ant and Dec I think it's safe to assume that not everyone gets a prison sentence for drink driving.