It took me a year, and that was the old 15 hour one and it took 15 hours. I did it at weekends and what with weather, waterlogged airfield (Redhill) etc etc and seven cancelled tests due to weather it took about a year start to finish. I planned to do it in 4 weekends but it didn't quite work out that way.
But I did it, I'm glad I did it, and no need to take time off.
Everyone advised against doing it part time but it can be done.