Caty, i haven't an idea about Nottingham but I have an honest response to you. Whether a place is good or not is more often than not to be decided by the person who is considering it. I would consider answering the following questions based on information gleaned from the academic circle publications, conversations beyond all my own assessment:
1. Is the department reputed?
2. Is it research led? If so, what are the areas they are working in? What, in other terms, is the distributed expertise of the faculty?
3. Am I attracted by the research of the person who shall supervise me?
4. Does this person publish well? Collaborate well? Do we seem to get along?
5. After this comes general reputation of the school, which no doubt is often an important factor. Included here, where are its PhD students placed now? Especially the department you are looking at.
These weren't in any order, but I suspect, the best option is to answer all of these, and try to see how much you can back these up with academic information.
Best!