I am not sure if my limited experience will help, but I did make informal inquiries recently. My job is rather technical/specialized, and my last trip to the UK was partially to meet with people in my field to see how things are done there. Since I was on a visitors visa, and looking for work would have been illegal (as well as pointless since I don't have a moving date yet), I simply called, briefly introduced myself and my situation, and asked if they would have me for a short visit. Everyone was very accommodating and happy to answer my questions.
Since I don't know what type of work you are in, I am not sure if this type of call would help you, but I found it to be very useful to gather information, as well as to make contacts in my field for when I do have a moving date.
Good Luck!