Pretty amazing stuff to read. Somebody learning to fly and planning to fly a King Air right away.
As someone who wanted to get a plane (or a share in something half decent) from nearly the start (and got shot down by all instructors I spoke to) I really admire that, and hope it isn't a wind up.
Instructors will really love such a student. Actually, not; most PPL-level instructors will be totally scared of such a student. He will need to get seriously well sorted out on the instructor front, with a real working ATPL man who is current on the type and can teach the right procedures right from the start. The stuff one learns in a PPL belongs to the Dark Ages, for someone wanting to fly IFR.
My input, knowing next to nothing about turboprops, is to get an N-reg one, and get an FAA PPL/IR. I doubt anybody will be willing to teach the type rating to somebody without an IR (certainly true for bizjets).
If the UK (or EASA, a few years down the road) manages to kick out N-reg planes, then the pilot will have to upgrade to a JAA PPL/IR and spend a wad putting the plane on G. That is about the worst case scenario though and it will probably never happen. All the same, I would avoid planes that would have massive certification issues going on G.