Hi Wal,
I think it could well be a good thing that the viva is so soon after submission, less chance to forget everything, just read a few key publications, think about the obvious weaknesses of your thesis, but don't do too much. I managed just fine on doing a bit of extra reading at weekends plus a read through of the thesis the night before on the train, in many ways having started work bfore viva day helped me quite a bit as I was not able to think about it too much