You can join ANY club in the country , i know some clubs that have members from overseas, yes it makes it hard to get to club meeting but you do get all the other benifits such as news letters, friendly advice and as stated the Aquarium World Magazine.
As for registering breedings , others find out what your breeding and may want to buy some off you , you find out what others are breeding and may want to buy some of others. You compete for the national trophies and get a nice cert for your fish room. The hobby also benifits because others talk to you about HOW you bred a species because they know you have ...etc etc so much to gain all round.