My memory tells me the numbers aren't correct, but I don't want to guess what they are, so just check the RAF website for the information, surely you can't get any more accurate information than from their website?
EDIT2: I actually looked at the web page for a bit longer and noticed that it doesn't give you much information about the tests; sorry for this useless input!
You need to go along and just give it your very best effort. If you can't do closer to 40 pressups and sit ups in a minute, you are pretty unfit. There are so few places for recruiting now, they can afford to be even more picky than ever, so you need to give it everything to prove you are worth it.