RAF Police is basically no more difficult than any other role if you do as much preparation as possible before you apply, particularly fitness and interview knowledge. The areas that people can't necessarily control are the AST and the medical.
Why does it matter about the make-up of people who apply? The Regular RAF is about 14% female overall, so you will always be in a minority. If it's what you want, go for it. But as Dog-Handling is a specialism, are you prepared, if you're not selected for it, to be involved in other duties?