As this forum is sometimes plenty of negative coments I decided to share my positive experience.
I attended one of the 3 days Gen Nav course run by Cat3C in Gloucester and I must said its absolutaley brilliant. Tony knows Gen Nav inside out and his little tricks are worth every penny. Also, the content of the books and the explanations are clear and understandable. I cannot recommend him enough.
If you are struggle with Gen Nav this course is a must.
I am not involved in any way, just a happy customer.