This has been done before. In short, there is no P2 unless the CAA have deemed the aircraft as needing 2 crew ie the bigger stuff. In that case you need to be type rated on type. Aerial photography? you will need a CPL to fly in that role anyway. If you are being offered this, you cannot (legally) be anything other than a passenger (unless you are the photographer hiring the aircraft), in which case it becomes a public transport flight. Cans of worms!
If you are being offered this and they want some money from you, walk away.