Becster...
Had an interview with both Gulf Air & Emirates about 3 years ago & both ints were held in London but to be based in Dubai. I believe the min age for Emirates is 22 but it might have changed now, not sure about Gulf Air. Quantas i believe you have to live in Oz to even be able to apply. If you fancy moving abroad to fly have you tried Quatar Airways, their recruiting at mo, go to flightinternational.com you'll find it their.
Good luck