Rivetjoint wind your neck in. Is that the only constructive bit of advice you can offer? Must be hard work being perfect.
Original poster,
You can resit them and people do sometimes pass aptitudes on their second sitting so I wouldn't worry too much. Joining the UAS would definitely be a good idea if you are interested in a career in the RAF. You might find you do better at OASC next time if you have had some exposure to what the service has to offer. Also there will be a lot of help available with your application and report from the Sqn staff.
You can also help yourself with aptitude tests by nailing things like speed/distance/time type equations as this will save up some capacity for other parts of the test. After saying that, there are parts you cant really improve like the hand/eye stuff as this measures innate ability.
Good luck
DS