Faithless, you, like Messrs Winsor, Marshall & Watson, are under the misguided view that all that is required to become a police air observer is to be able to use the camera equipment and that there is nothing remotely "specialist" about what they do or the environment in which they operate.
I say this, not as a police air observer, but as a pilot who has worked alongside many of them for the past 15 years. When you can honestly add their levels of skill, ability and knowledge to your CV along with your "camera time" you might get a look in.