Ho Sophie-you would of been given a membership number when you paid and joined the fanclub, usually it's on a card in the membership kit, and recently on the front of the envelope (top left hand corner)of the crowded house xmas cards that went out.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .