DP - the scholarship interview is AIB, and you'll have an automatic place at BRNC on completing A-levels if you a) get a scholarship and b) get the minimum grades.
Be aware that there are probably only two aircrew scholarships awarded for the one year, and only one for the two year award. Not getting a scholarship is not a failure, though. Your AIB pass is only valid for 12 months, so you may have to go a second time.
The flip side of applying is that you get to complete FATs. That's fine if you score high/very high, but less good if you score lower, and say get a bare pass, as it will count as one of your two attempts. It's generally thought that people peak around 19-20 (learning to drive helps, they think), so taking the FATs at 17 may work against you, or it may work for you.
My honest opinion is that it's not worth applying. The award is pennies, albeit worth something, but not that much. If you are good enough, you'll pass just as easily at age 18, or later, if you go to university, so there's really not that much to be gained. My guess is that there are over fifty applicants for each scholarship. The RN currently seems to be leaning towards giving more scholarships for engineers, as they've got loads of aircrew applicants to choose from without having to offer more carrots.
Check yr PMs.