My Vampire Grandad The Fang Gang Series, Book 1.

Life for Jonathan Leech is on the verge of taking a toe-curling turn for the worse. Or is it? He's about to discover his family's darkest secret. Grandad! But that's not all. Jonathan makes some unusual new friends who are going to teach him a few bloodcurdling things about himself, too...Meet Jonathan and the grisly neighbours of Goolish in the first of a brand new series about the Fang Gang.