Leonbrumsack,
if your only problem is that you are too young (and if you are too you for the Air Atlantique thing you are too young for them all) you really have no problem at all. At school they are probably trying to push you towards uni because even when the airlines are desperate for new pilots the path to becoming a pilot is a difficult and unlikely one. the fact that you have no experience at all of anything beyond your school years is not going to help you either.
So, as you asked, what do you do? Apply anyway. and then start thinking up your backup plan. The one that is so red hot that the airlines will be falling over themselves to steal you away from it. Friends of mine who have all been successful with sponsorship applications have done various things, including being a lawyer, engineer, teacher, ITU nurse, archaeologist. As you can see everyone on my list had to get a degree first in order to shine so brightly that an airline wanted them (BA in this case). There are people out there who are good who didn't do a degree. They have generally managed to acheive this level of brilliance before needing to go to uni. So go on and apply to a uni course you like the look of. The subject doesn't matter. The parties will be the best in your life, and a full array of societies are just waiting for you to be the best president/secretary/sports team captain they have ever had just so that you can show on your sponsorship form how good you are. And when you finish you will still be 5 years younger than the average age of people on my BA course at OATS.
One last thing. Don't wail 'but I want it nowwwwww'. It doesn't show maturity and wishing whole years of your life away is not a good thing.