i had same issue until i just practiced and posted some threads on here. I use OAT PPL CD rom.
Managed to pass nav today without even using the books, just the cd roms.
Confuser is a very accurate example of the exam. You get one PLOG to complete and one route to draw and about 18 of the questions are on this so be very accurate with your PLOG.
Then last 5 are on Nav Aids.