I would just echo what has already been said re: the UK. It seems pretty impossible to get much useful insurance at all for freelancers.
I do remember a piece from the BHAB about getting suitable wording added to hele aircraft insurance policies to cover freelancers. If you have a hele owned by one party and a second party use it for AOC work, then it is normal that the aircraft insurance covers both owner and operator. It is possible to also get it to cover the pilot, if he is self-employed too.