Cheers H, the ceremony will be outdoors (Mount Annan Bontanic Gardens) and the reception inside. I've emailed the website I've mentioned for some more info on those lenses as well as a 430exII flash, I'll enquire about the lens you've mentioned as well.
Depending on what SWMBO says, I may even go all out and hire a 5D MkII as well
Cheers,
Ben