Try to avoid flash and use a high iso to get the ambient lighting, it's always great in places like Cathedrals. Which lens depends on where you are in relation to your wife, I suspect the 55 - 250 will be the most useful, in fact if you are using built in flash it probably won't be much use anyway.
Take some nice photos of her in her gown outside with the cathedral as backdrop, stick to the long lens, Av mode, f4 or as close as you can get to that, use the pop up flash here as the camera will automatically use it as fill flash to reduce shadows.
Most of all, remember to take the camera away from your face occasionally and enjoy the day!