Agreed - Gen Nav & met. Really struggled with time on the Gen Nav exam, you have to work pretty quickly to get everything finished within the time allowed so keep an eye on the clock. Met I also really struggled with, found the subject interesting and thought I understood everything but the questions they ask you in the exam are a nightmare! Thought I was good at decoding TAFs etc but they are phrased in such a way they are difficult to decide which answer to go for, as someone told me - go for the least wrong answer.
As you have probably heard a zillion times before - use the briston question bank, also the oxford met CD I found really useful.
Good luck!