hello just learning,
from what i gleaned from your thread you really don't have to buy anything. Thekit lens that came with you camera if indeed it was kit lens will suffice.You already have everything you need. I believe you also have a 430ex flash. you are all set equipment wise.
I say this becausei'm thinking,you or your daughter didn't hire are pro because you or she might be thinking of saving herself or you a little money and you going out and buying a new lens just defeats that overall thought of "saving".
Now others say a pro will do a better job. there is always that possibility especially since you yourself say you have little expertise. But then again that works two ways. A person who doesn't know much about photography could care less if pictures were taken with a point and shoot camera. these people only care to see faces and places clearly in every shoot. These people are not nit pickers. Just as long as the pictures are clear and sharp and with vibrant colors it will be okay to them and you have the equipment to give them those kind of pictures. Sure pros will take a better angle on the shot and better lighting etc. but then will it really matter to the people looking at the pictures??? Also just think of how proud you daughter will be showing off herwedding photos that her FATHER took.
Maybe later if and when you seriously getinto all this photgraphy stuff that you will notice faults [if any] with the pictures you took. Sure there won't be any re doing of the pictures but then again that's part of the learning curve. I have been there. People i take pictures of, never reaLLY CARED on what equipment i use or the style used so that photo will come out looking good. what matters to themis it looks good. Believe me you already have the needed equipment to shoot you daughter's wedding. As long as you do your part that is to look into the viewfinder and focus, the camera will take care of the rest. That's part of the beauty of digital cameras unlike in the old days when film was used you really have to have an undrstanding of photography to be able to take pictures.
Just go there have fun take pictures am sure everything will turn out great. I'm sure you will make your daughter proud of the pictures you took.[]