Sorry - a late reply to Julian's post of 26 Feb 02, 1510.
I studied for my ground exams conicident with my PPL training and did one a week with Ron Heyter (this was in 96, when he used a club called Airbourne). Great guy and one a week was about the sort of rate to aim at; gave you the chance to read the books, try a few sample questions, then an hour's brush up with him before sitting the exam.