Hi, there is a UK group on http://www.avmsurvivors.org/
that you may wish to join. There are other members who have arm avms on that group; perhaps you can get some doctor recommendations. There are over 75 members with arm avms on the website from all over the world.
Your condition sounds like Parkes - Weber Syndrome, which is caused by a mutation in the RASA1 gene (http://ghr.nlm.nih.gov/condition/parkes-weber-syndrome)
. PWS may be a spontaneous mutation, but can be inherited.