hull has (obviously) waaaaaaaaaaay fewer clubs than london, but there's enough to be going on with, including one at the SU which is reputedly one of the best in the country. I can't give any specifics, since it's ages and ages since I really investigated the clubs in Hull.
Cultural mix - ten years ago, when i was growing up in Hull, it was pretty much 100% white british. This has been slowly changing, and today you'll see black or asian people every time you venture out. Coming from london though, it might be something of a culture shock! Some of the locals aren't the most tolerant of people, their first experience of people of a different culture being when they had a load of kosovan asylum seekers dumped onto their impoverished housing estates - they're understandably upset and naturally have a fear of the unknown, much like other areas of the UK a few decades ago. I don't think this manifests itself as violence regularly though, at least not outside of the housing estates I mentioned.