If you were both single then you wont need the decree absolute - it was a legal document to show my previous marriage was closed. I thought it was a stupid requirement because in order to get married again I had to show this to the registrar but if UKBA need it and asked for it I had to comply...
I am not sure if you would need to put any documents in to show you were single - we didnt for Rina.
Ah we did put both birth certificates in the document bundle too.
I had a wallet A4 size that I put a header document listing in order the documents asked for - then in each sleeve put the documents so everything was presented neatly and concisely - makes it easier for the ECO/Case handler to go through the documents.
Cheers
Tone