Hi Matt,
I vaguely remember that you have to be able to cover the ground at a rate of a Half a mile every three and a half minutes.
However, the RAF fitness test is now a shuttle run over 18, 20 or 25 metres, depending on how much of a short@rse you are. You may find the requirement if you search pprune under iot or oasc.
I don't think it's part of the fitness test, but later on, during IOT, you may have to do a set number of press ups and sit ups. This is the best information I have right now.
You have done well to go forward for OASC-don't screw it up by being unfit or not practising your maths. You owe it to yourself.
Word hard and be lucky!!