James, at 52, you are DEFINATELY not too old to learn to ride, the only regret you'll have is not starting sooner as (most likely), you'll find a new love for the road on your bike.
As people have said, it's best not to practice before your MSF course as it can also form bad habits that are difficult to "unlearn" during the course.
Keep at it, don't worry about the "road rash" on your bike, it's all part of the experience we all have!