Lots of excellent advice above, which I can but endorse and say hear, hear! Like others I flunked selection first time round, but was encouraged to come back for another attempt. I think that invitation triggered a positive response in me, and made me even more determined to justify their faith. The fact that it was a familiar pattern next time round made it less stressful for me also.
All this was many many years ago and involved empty 60 gallon oil drums, planks of wood, lengths of rope, and crocodile infested grass. No doubt the scenario has changed greatly, but the purpose remains the same, to find the next generation of RAF Officer Aircrew. You sound just the sort they are looking for NDW! They only need to be convinced of it. Good luck on your next attempt.
Chug