Research in the United Kingdom
When conducting research in the United Kingdom, be sure to prepare yourself by finding out as much as possible about the archive you will be visiting. As with research in the United States and elsewhere, the vast majority of repositories in the U.K. have good online resources to help you locate the specific sources that you are after. Although some archives have a better web presence than others, be sure to do what legwork you can in advance. And, as always, be sure to consult the relevant rare materials catalogues in advance of your visit! If your library does not have the particular catalogue for your research, track it down via Worldcat or some other such database. Potentially useful repositories and resources are listed below, though more are created everyday. If you don't find what you need below, google it! You may just find what you're looking for!
Major Research Libraries
Additional Resources for British History and Preparing for your Research Trip
(As a general rule of thumb and if you're able, be sure to attend the seminars and meetings of the Institute of Historical Research in London, and the departments of history at Oxford, Cambridge, and other U.K. universities.)