If you are looking for Revit content, especially UK content, its worth visiting Revit Store.
Revit Store has been setup by Ian Howard, who used to work for Revit Technology as their EMEA Trainer before Autodesks acquisition of the company. Ian has worked in the Construction Industry for the past 30 years and 15 of those have been as a professional Trainer and Consultant. He original qualified as a Structural Technician and later moved on as an Architectural Technologist. He had a fundamental role in the early days in the creation of Autodesk Revit content, helping drive the UK market.
Ian's business is now based around Training and Implementation of all Revit platforms. Also he is a Content Developer creating numerous Content Family Libraries for a large international software vender and a number of Architectural and Structural companies.
Take a look at his website, also check out the tricks and tips pages.