siy, I'm struggling to understand exactly what it is you are asking?
You say you failed your aptitude because of an alarm clock and being unwell. You know that, and you know the solution for the future is to get a reliable alarm clock, and dont go when you are unwell. No need to get stroppy for having this perfectly reasonable answer pointed out to you, but you seem to KNOW why you failed, and know what to do about it next time. So clearly this isn't what you're asking?
You say the AFCO said you were one of the best candidates they have seen. Good for you! Why is that relevant to us?
What you seem to be asking is.... Do I really want to join the RAF after having failed OASC once? Only you can answer that question after doing research into whatever trade it is you want to go in to. If its what you really really want, then why are you asking "something" here? Can you clarify what it is you are actually asking?
Just a suggestion of an alternative, and possibly more appropriate and relevant resource for asking this sort of thing is:
http://www.aircadetcentral.net/forums
There are a fairly large number of people in a similar position to yourself on this forum, so you might get some advice there too?