The Public Record Office is the main repository for Family History Sources in England. It is making efforts to upload some of its records online, and will become increasingly useful. It has an online catalogue of its holdings. Its Family Record Center in London is open to the public.
A superb site is Access 2 Archives. It contains catalogues of archives held across England within record offices and other repositories.
The Historical Archives Commision (Archon) has a search facility, which can be used online.
The LDS church houses within many of its churches, Family History Centers, please don't be intimidated, anyone is welcome, and the centers are mostly run by volunteers, who are often not members of the LDS church, they do prefer a phone call so they know you are coming. (English Family History Centers) From the Family History Centers you can order for a nominal fee, almost any record that the LDS church have gathered over the years, which is actually mind-boggling. This is particularly helpful if you are abroad, or cannot take the time to go to the various libraries and record offices around the country.
Most Family History Societies welcome new members with open arms! They also hold copies of many resources relevant to the Family Historian, as well as indexes to various records. Volunteers have also produced a National Burial Index.
Again, and again, I have referred back to the GENUKI web site. Thorough and extensive - the best information portal around for the UK.