Look mate, if you get a shot at FSP, then the final yes or "thanks for coming" will be determined by how you perform over the two weeks. Don't worry about your age and non-uni background. And you have some flying...to me that displays some motivation. I reckon if you have deep drive, good learning and aptitude in the air, work well with others and express yourself well, all under a bit of pressure...then the FSP will show this off. For those that are not as blessed this will show up too and no amount of pretending will cover it. The selectors are very experienced and the process is robust. So if you get a shot, just go for it and as I said before, be yourself and enjoy the ride.
As for getting to FSP, roughly 250-270 are sent to Tamworth for screening annually to find about 150 BFTS entrants including all three services. So just getting there is pretty competitive. If you miss out on FSP you should seek feedback on how you can be more competitive. Good luck
RM