Hey,
I went to manchester in november and its not that bad, although i have read that some people had awful experiences, but still got offers, so i wouldn't worry too much about it.
The essay but is not an exam at all, its basically 2 questions that you need to answer in continuous prose. One of something subject related that you are currently studying and another on recent health related issues in the news, or something like that.
Me and some of my friends had questions based upon naming 5 drugs and what they do, different ways they can be administered, random mental arithmatic questions, wether pharmacists should be able to prescribe or not and things like that, cant remember any more.
Am sure if you root around some of the other threads you'll find out some more questions/info/tips kind of thing. It was also really short as far as i remember!
Good Luck!