Best to stick with one film but if you must have more just use a camera bag with multiple compartments. I did weddings for many years using only Kodak Vericolor III which held great detail in white wedding dresses and cakes. Sadly it is no longer made. Good luck on your upcoming shoot.
First - I used one of these Fanny Packs for years to carry my wallet, phone, ... quite handy. There were various separated pockets that could sort the film. In fact I may dig mine out for similar needs.
Second - I'd ignore the nay sayers on your film choices. I'd feel very comfortable shooting a wedding with the number of rolls and types of film you have chosen. Last wedding I shot was done with 9 rolls and two types.
Third - With regard to the "high pressure" you mentioned in the title. Relax, weddings are like track meets, there are a few short sprints that are separated by long stretches of waiting (and schmoozing). If you know what's next and where you need to be it's it's easy, just make sure you have a fresh roll loaded before something important starts.
Mark Barendt, Ignacio, CO
"We do not see things the way they are. We see things the way we are." Anaïs Nin
Whatever you do, if you are ever in the U.K. and need one of these remember to describe its use rather than use the name
Oh yeah, huh! We are indeed two peoples divided by a common language.
Walking into a shop there and saying to a woman that I need a fanny pack could get my face slapped.
Even worse would be if she weighed 20 stone, had a moustache, and tried to take me up on my "offer".:o
A new name is definitely in order-maybe "small waist pack".
One film, maybe!
I used to use two identical cameras (Nikon F's) with flash units, same film and alternate cameras to insure if one failed I still got results when I did weddings commercially.
Now that I use two Leica M7's, only one has a flash. One has K64 and one K200 of which I have small supply left. The K64 camera and flash are used with a 35mm Lux ASPH and the K200 gets a 21mm ASPH for shots from the back of the church and a 75mm or 90mm ASPH for shots at the alter.
With today's SLR's I would think that one camera with a good zoom and dedicated flash would suffice with one film. Possibly changing to a higher ASA for available light shots.
You must scout the church before hand preferably at the same time as the wedding to note light levels and access paths. I usually leave a bag with film etc in the loft area readily positioned. I always make contact with the server and define the rules for flash/no flash and access beforehand.
Find the rooms where the bride prepares and where the groom prepares.
Have a step by step plan from the arrival of the party to its departure noting when and where you will photograph. Good luck!-Dick