My MIL sorted out most things for us too!!
Is there anyone you or anyone close knows who does photography as a hobby? Thats how my uncle got into it, and even though he failed his photography a-level (i didn't even know they did one!) As a family we've had to put up with him telling us where to stand etc forever, and we know his pics are good!
Where do you live? (the place in your sig i have no idea where it is!!)
If you want ones at the registry office/church, give a few people their camera's early so that they can get them for you (if you don't bother with the "official" guy) Our registry office wouldn't let us take pictures until after they'd done their bit then let us pose with the register, so defo worth checking with the place you're getting married before you decide to take the plunge hiring someone cos they're the pictures i wish i could've had... to show the real emotions, nervousness etc!
And what someone else said about writing down the special pictures you definately want... we did that, cos G's parents are divorced and he's not got a picture of him, mum, dad and sister... so we made sure that one was done, it was like a roll call, but it made sure we had them all!!!
Good luck with it whatever you decide
xox