Bananas is this part of interview nerves? When you are on the threshold of something big , which is also something which you have to commit to, and you have to therefore give up other things which you might like, then having doubts and questions is normal......almost like firming things up in your mind before taking the plunge to commit to maths.
Being a vet isnt easy, getting into vet school is really hard and you haven't got any vet work experience so I say stick with what you know and what you are good at and relish your interview chance.
See if you can organise time with your local vet over the holidays after your interview. I once met a vetinary epidemiologist- you could always do vet med as a postgrad.