Roz, please have a look at the website for the campaign to open it as a cinema.
Originally it was the Rialto Cinema, then the Granada cinema. It was a rather grand cinema in its day.
It then reopened as the Granada Bingo hall before being taken over by Gala Bingo, which it remained until very recently.
It has never been a church.
So I'm not sure where the planning issues come from. It was a cinema, it is a cinema building (and potentially quite a nice one).
I will be preparing a 'what if' on this soon. Check out http://www.whatifsydenham.wordpress.com soon to find out what it COULD look like.