There will be at least one reading from the Bible.
If you wish you can have more and you can also include readings or poems that you like from other sources. I do ask to see any readings as I have heard readings which sound great when read to yourself but which don't really work when read aloud to a lot of people! But usually that isn't a problem, so please ask.
I strongly recommend you have a look at the Church of England web site wedding planner too. It will show you the words of the readings.
There are set prayers (see the Words of the Marriage Service) but you can use prayers from other sources or write your own - please talk it through with me!