You cannot be an AEF pilot without a VR(T) commission unless you are a regular QSP or QSN or QS anything for that matter (take note of next). To get that VR(T) commission you have to be recommended by the OC AEF. If you are from a civilian training background (or not QSP background) but have lots of SEP experience and have passed ATPL exams (latest guidance I understand) and are fully aware of the ethos thats supports the voluntary time you can give to the ACO then there's no problem. If you don't understand the TLAs please use google.