Yes, you will be fine! The report you have prepared and submitted to them should be the basis for all their questions. So ensure that you understand everything you wrote and why, relax, have a good, open attitude, and you should be sorted. Curve balls are just curve balls - there may be a few - and you might be able to answer them, might not - either have a try if you think you can or just admit you don't know if you really don't - those are the two best (arguably only!) options and either is fine! This is the advice I give based on my progress report viva and my final viva. All the best!