First, there is to say that everything you are about to read contains spoilers, but that should have been already clear after reading this post's title.
____________So, I don't want to be responsible for you breaking your promises you made yourself. Here is a link leading to my source*. It's your choice ;). Maybe I'll edit it later, but right now I just don't find more or better information. Even our beloved guardian TV&Radio blogs aren't writing anything about it ATM.
*It contains a few "Wedding of Sarah Jane" episode pictures, a short plot summary and a link to the recent Didital Spy interview with Elisabeth Sladen (Sarah Jane). If you want to read only the interview, well, then here is the link.