Durham University - Imposter SyndromeWatch this thread
In terms of the exam anxiety, I know exactly how you feel. I get the same way, but more out of a claustrophobia - I feel like I can't get up and get out of the room if I need a break. If possible, would you be able to contact some sort of student support at Durham? Perhaps a counsellor who could help you through your fears, but also help make things easier for you. For example, get put in a room on your own to do your exams in peace?
I hope this helps!