If you are preparing for an interview to get into the RAF, the recruiter is going to be much more interested in you and what you have done in the past than in what you have mugged up on. In the interview concentrate on the positive things you have done - have you done Duke of Edinburgh award...
If you are set on getting married, then it would be a better idea to do so sooner rather than later. The Army does not recognise relationships other than marriage so you have no status towards each other unless you are married. There is always a lead time to postings being available so the...