To Whitney,
Doing a wedding photo shoot is non-trivial. Youre getting the reaction that youre getting because your degree of knowledge and preparation seems equivalent to someone having a hammer and a drill, being asked to build a house for a relative who cant afford to hire a real architect/contractor.
If you have 9 months, then you need to acquire a few things:
1. Experience with your equipment (and perhaps some new equipment).
2. Experience shooting in the typical environment
3. Experience with light modifiers (flash, etc.).
4. Knowledge of basic composition, posing.
5. Knowledge of post-processing
Perhaps, the starting point is to look at various wedding portfolios (there are many on the web), and various wedding publications, and get a sense of the kind of images that are common, and discuss these with your customers. Your goal here is to get a sense of what they expect and to figure out the minimum deliverables. If all they want and expect are two shots of them at the alter, great. Chances are, they'll want more.
Once youve got a clearer idea of the target, you need to scout out suitable places which replicate the shooting conditions you will have and try to shoot the photos using a willing (or susceptible-to-blackmail) volunteer. Then look hard at what the results are and decide where you need to improve.
For example, you mentioned that the church in which youll be shooting has fluorescent lights and dark woodwork. This means that unless you know how to adjust the color balance, youll have all kind of weird tones. The dark woodwork will skew your cameras lightmeter, and will most probably cause you to overexpose. This means that you will need to get a good idea of the exposure to use (you need to expose for the highlights), and then lock that in by using the manual exposure.
If there is just not enough light for you to get decent images, you have options: a flash (assuming one is allowed at the wedding), a faster lens than what you have ($$$), and/or a camera body which can handle high ISO values with minimal noise (again, $$$ or rent $$$), and/or additional lighting equipment (more $$$). Learning to use a flash is a non-trivial exercise as well, as you need to figure out which flash mode you need to use, the amount of power it has relative to your shooting distance, whether a flash modifier/diffuser is needed, etc., etc.
Although there is usually not a lot of movement during a wedding, there is a lot of variation between the lightest areas and the darkest areas. You need photographic skill to ensure that all relevant parts of the scene are recorded with enough detail. That skill is obtained by learning and lots of practice.
If youre the only photographer at the wedding, youll need to be in many places at the same time. Since that is usually difficult for ordinary mortals, youll probably need to work out a script with your customers in terms of the shots that you will make (including your position, the angle, the degree of zoom or closeup), so that you can move smoothly through the sequence without becoming the scene yourself. Experienced photographers usually know where they need to be for each part of the ceremony, but you wont have the benefit of that experience.
After all is done, theres the processing of the pictures, weeding out the out-of-focus, under and over-exposed ones, ditching the ones where the composition or posing is unflattering, etc., and preparing a deliverable (prints? CD? DVD?) for your customers. Again, post-processing is non-trivial, especially with all the tools that are available.
One piece of advice that I can give you, is to try and get invited to as many weddings as you can, either as the friend with a camera or as a second shooter. Watch what the pros do and borrow all the good ideas you can (thats called hands-on-learning). Then try to replicate what you saw them do (that is called really hands-on-learning).
Remember also Murphys Law. You know, Anything and everything that can go wrong, will. The counter to Ms. Murphys machinations is preparation and anticipation. Backup equipment, backup shooters, backup batteries, backup memory cards, backup hard drives on which you will store your photos, etc.
Thats why you have gotten a less-than-stellar welcome there is a large gap (or so it seems to us from your posts) between where you are now, and where you need to be to successfully and reliably deliver on one of the most important days in the lives of your customers. It can be done, but it is, as Ive said before non-trivial.