Oscar
You have absolutely nothing to lose by applying for a 6th Form Scholarship. You may get it. You may fall short and get a Flying Scholarship (if that's the way it still works). You may be unsuccessful. In any case you will earn valuable experience of the selection process.
I failed to get a 6th Form Schol and HAD been an air cadet. I DID get a flying schol and was graded as "average" from that and so didn't get a stab at pilot when I left school. But I AM a pilot now, so it can't have done me too much harm.
Just remember that you only get 2 goes at the pilot aptitude tests. Full stop. So hone those eyes and thumbs on your playstation.
Whatever you decide, good luck.