The AA Driving School do a special offer for the Armed Forces - I will try to add the details later.
I think that the idea that the Navy automatically teaches personnel to drive might have become urban folklore, perhaps based on uncles who did National Service talking about guys learning to drive a few years ago.
Like driving other vehicles Ginge unless your billet requires you to drive a motorcycle then you won't be put through lessons. I don't know of any billet that does require driving motorcycle unlike cars, lorries etc.
So I guess you maybe to use the learning credits towards lessons. But don't take that as gospel