<bit late>
The Thom Nav book is fairly useless IMHO - makes it all far more complicated than necessary. Nav isn't complicated (a retired Vulcan pilot told me it couldn't be difficult, because if it was Navigators wouldn't be able to do it...
) but the Thom book confused the hell out of me. Learn how to use the whizz-wheel and then sit down with your instructor one wet foggy day and plan a couple of flights. Teaches you all you need for the exam...
</bit late>