Re: RN application-Pilot/Obs
I am pretty sure that the RN will no longer accept anyone who does not pass for both P&O since the cost of basic training (BRNC etc) is lost and allows fewer subsequent options should that person fail during flying training.
You might as well forget any notion of joining as an observer and transferring to pilot later, though there are a handfull of examples, it almost never happens.
Good luck anyway, it is a fantastic career!