Hi Reyllock,
Dont know if you noticed but this is a pretty old thread although still very relevant.
Call these people
www.escapees.com
They might be able to point you in the right direction. I cant see how an American based company can write in the UK, but if any one has the answers these people will.
When you get to the home page, click on endorsements on the top. There are a couple of insurance companies listed there. I would still
call escapees though and talk with them. You cant be the first person trying to do this overseas and I just bet these people can help.