With this in mind how do you prepare for your viva? This is something that I asked quite a few people and I came to the conclusion that it can vary dependent on the subject area you are in and your potential external examiner. Personally all I did was re-read my thesis in the couple days before. Essentially, you should have absolutely nothing to worry about if your wrote your thesis yourself and did all the research. In my case I was relatively happy I met the criteria. Although, I am sure it is probably a good idea to re-read some key papers surrounding your thesis and certainly some of the papers of your external examiner.
Next step, getting an academic job which doesn't involved moving every 6 months!