Passed exam this last week thanx to all the constructive posts in here... definitely some nervous moments between clicking submit and getting the result.
Can't emphasise enough spending a week and a half to get up to speed doing practise questions.
Do a course somewhere! I found the UNSW course to be sufficient to pass, if a little too quick in the delivery. All the material came so fast it was hard to keep ones head above water. Took me a good near week and a half just to be able to 'get it'. What was good was the questions covered in class were way harder than the exam so prepared one well.
My ATPL Performance exam had some stuff from Flight Planning in it so you may want to do this one next.
Good luck.