I love the comment about my sister...you'd have to know her but telling her to suck it up would not work She's a sweetie don't get me wrong, but has serious anxiety issues and is in a new relationship and just lives in her own little world...I don't think she'd be much help even if she were trying unfortunately.
As for my future MIL, I think she might be really interested in helping out, my fiance is going to speak with her tonight about it. And I know that my Dad's fiance would love to be as involved as possible but I don't know her as well as my future MIL so I may be more comfortable with the MIL.
I did find one group specifically for London Brides which has been helpful, but it's very small and not very active which can be annoying...I like a nice active board! And I love your suggestion or "Weddings for Dummies"...that's totally what I need