Mattd, at 17 the AFCO is interviewing applicants for direct entry. That you are intending to go to university first is not a problem. The interview therefore would be identical to one you would get later on.
If you want to join a UAS you are going to need that interview sooner anyway.
You say you are thousands of miles away. New Zealand perhaps but for Spain that is a bit of an exageration. A RyanAir flight, at the right time, will cost you not a lot and take only 2-3 hours. With the right timing, nearest AFCO etc you could even do it all in a day. Now that would be good to demonstrate keeness, initiative etc.
PM me if you wish.