Finally finished Master & Commander after being distracted by exam revision. I must say, I'm glad to have read it, for it was very engaging and, indeed, enjoyable to read. Also stormed through Mr. Midshipman Hornblower, which seemed a lot simpler after rather more technical Master & Commander. Still good, though.
I'm now about a third of the way through Lieutenant Hornblower. I've still got Hornblower and the Hotspur left to read after that, then perhaps I can consider buying more!
Thanks to all who recommended them!