RAuxAF
Mitch, hi
DTWH is spot-on. If you want to join the RAuxAF as an Officer, you need to find a RAuxAF unit, get selected to join them, get pinged as an officer candidate, pass the regular branch selection test requirements, pass the rest of OASC, and then do the ROIT course (or whatever suceeds it). This all reflects increasing the professionalisation of the RAuxAF, which has to be a good thing.
The major point to note here is that the most - though not all - RAuxAF units have relatively few commissioned slots, and they often promote from the ranks. As a result, it may not always be possible to join direct as an officer. Pls PM if you want to discuss.
Best of luck with whatever you decide to do.
S41