The BBC synopsis for the episode follows, which might be considered a spoiler:
As the Doctor makes his final journey to the shores of Lake Silencio in Utah, he knows only one thing can keep the universe safe – his own death – in the concluding episode of this series of the time-travelling drama. But has he reckoned without the love of a good woman?
The Wedding of River Song: Trailer, BBC, via YouTube - may not play outside of the United Kingdom
The Wedding of River Song: Next Time Trailer, BBC, via the BBC Doctor Who site - may not play outside of the United Kingdom
The BBC have also released an introduction to the episode in the form of a special scene taking place before the story begins: