I have no real knowledge of the mil careers you talk about, but we've got an ex-FC at LHR and he's doing well.
I'd imagine the skills that would make you a good ATCO could be developed in an FJ cockpit, or as an FC, or mil ATC, or many other military trades.
Teamworking
Working under pressure
Prioritising
Multitasking
Situational Awareness
Decisiveness
It seems like to want to be a WSO, so be one. The skills you learn there will be just as valuable.