This is very much a subject close to the hearts of ALL wedding photographers and is something we have little control over.
Whether you have a church ceremony or a civil ceremony, restrictions with regards what photographic coverage is allowed are usually present. Be it a grumpy registrar, or vicar who feels it not necessary to have photos in the church - I have encountered them all. Some are very reasonable, but often they have not communicated with YOU (their client) what is or isn't allowed.
I suggest you therefore get clarity on what it is they will allow, and ensure this fits with what you want - after all, you pay for their service, so why should they impose restrictions upon you that don't fit with your brief.
Here's an example of when things go wrong - who the photographer is I have no idea, what was agreed before hand, again, I have no idea.
I always talk to the vicar/registra before the ceremony to find out what they will allow. However, if this is different to what you wanted then it's often too late to remedy it. I recently had a bride use the words "you have been given Carte Blanche to shoot whatever you want in the church" yet when I spoke to the vicar I was informed in no uncertain terms that I could not take a photo of the bride entering the church, that I was to stay in one place, not move (at any point...not even during a hymn) however could take a couple of photos (but not during the actual 'ceremony words'). Ummm.... a little different to the ideas I had in mind!
It's worth noting, when I shoot a wedding I awlays have consideration for the event itself and act discretely, with the end goal of producing images to reflect your day (after all, that's what you pay me for).
Finally I'll leave you with these few words I shared with a vicar at another recent wedding - some of you may be surprised by this (but it's quite often the case)
Matt: "Hi, I trust you're the vicar running proceedings today?"
Vicar: "You must be the photographer. I don't like photographers."
Matt: ".............. gasp!"
Really, does anyone desirve to be spoken to like this, not least you'd think by a vicar?