Firstly, I have a PhD myself and so understand going through the viva process. I would read through your dissertaion. I am assuming that you have already submitted. I would prepare the types of questions that examiners ask, particularly those stressing the original contribution to knowledge. Then I would organise a mock viva. This could either be in person , depending on where you live. I go to London frequently The other possibility is through Skype.
My PhD was in Higher Education, which means I understand topics related to Education more generally.
I used qualitative methods. I have taught Research Writing to pre-doctoral students.
Please feel free to contact me for more information
Alice