I was once an instructor at Jerez and recall the 17 yr old who arrived just in time to celebrate his 18th birthday on an Aer Lingus sponsorship.
Nobody will give a stuff how young you are. Its maturity that counts. If you avoid the pitfalls of the brothel the bar and the sunbathing and present yourself as keen, able and professional then you will be well respected by the staff at the school. Age has NOTHING to do with that.
Enjoy,
WWW