Unfortunately there is no such thing as piltos asistant anymore as someone has already stated.
Finding any kind of right hand seat job that doesnt require a type rating is like finding hens teeth, it isnt going to happen.
It is now possible to fly the BE200 single crew for public transport but as I was told by an operator a couple of years back it sounds like the CAA dont want a non rated pilot in the R/H seat, they would rather have a passenger!
The king air and the C525 are the last single crew turbines on the UK register that I know of that are used around where I work.
I heard of a guy who had 600 hours in his logbook right hand seat in a 525, when he applied for his ATPL it was bouced because he didnt have a type rating, the aircraft didnt require 2 crew and he was effectively logging time in a legal document that he wasnt entitled to. I would suggest buying a second logbook and log it in there. If you are not performing duties of a required member of crew as stated in the flight manual the CAA will not be impressed.