Muslim convert, how do I tell my family?

I think my parents will be fairly supportive, at least my mum. My parents are liberals. Mum is British, Dad is American, and we have lived overseas for most of my life. My dad lived in Pakistan when he was younger, and knows many Muslims. He is accepting of Islam, but he often criticizes the way it treats women and whatnot. My mum seems to be accepting of Islam. I have not been eating pork or gelatin for the past year, which my dad has been weird about, but has accepted it. Should I just tell them? My grandparents on both sides are Catholic and somewhat devout, so not sure how they would feel. Any advice?