Hi Luke,
Its been a couple of years since I had my interview with Oxford and I went for a white-tail place so things may be different. That said, as this is an interview for an ab-initio course they aren't expecting you to have in depth technical knowledge at this stage. They are more interested in determining your motivation and interest in aviation. If I remember correctly they asked me how a wing creates lift or a very basic principles of flight question along those lines, possibly the four forces acting on an aircraft. They also asked me what is meant by a glass cockpit and what is meant by fly by wire aircraft. It might be worth learning a little bit about Volotea's fleet just in case. Again, nothing too in-depth, just enough to show you're motivated enough to do some research.