If you can get holidays from work, at least try and do 2 weeks worth full time and the rest part time. That way PMI can be done properly and hopefully you will be starting to get the briefings under control.
In the meantime, open that BAK book and start refreshing your principles knowledge. Things like, "why is lift less than weight in a steady climb?" or "what is half rho and do we have control over it?" etc etc. You will be surprised how much you have forgotten.
Good luck with it and believe me, you won't be first to question your sanity half way through the course. Just keep on truckin'
In-cog
P.S. - Do you have your NVFR? Has to be done prior to the F.I.R. test.