It’s an area all bloggers would rather not get involved in, but it is best to be aware of the principles of libel and how it applies to you as a blogger. Mike Butcher, has written a very useful and informative guide to Libel and Defamation Law for bloggers. Read it and bookmark it.
Council officers might also refer to the Civil Servant social media guidelines recently published by the Cabinet Office. They are succinct but useful.