Thanks for the help and advise.
It's already taken me longer than 2 days to learn 20 letters. Did you mean 48 hours of study? I must have studied for much less than that so far. I have the hardest (longest) ones remaining to learn. Still - my mates at work are well impressed already.
I should nail it this weekend, along with book 5 - Radio navigation.
Cheers,
Alex