Guess it's getting exciting now that the letters seem to be coming out!
Thanks to everyone who responded to my spiral of doom there - good to know normal people definitely do exist in Oxford! (But, just so you know, you might find your good nature being completely abused as if I start having more panic attacks about stupid things)
Stumbled upon the Students' Union site. It's not exactly the best website in the world but it had just about enough information (added to the responses from here) to calm me down enough to think about it properly. New life plan: no making rash decisions after mental days at work - will be cool, calm, and collected from now on.