The General Baptists and Particular Baptists came together in 1891 to form the Baptist Union of Great Britain. Their Baptist Handbook of 1896 is available free from Internet Archive and contains, among other things, lists of officers, member churches, ministers and personal members.
The Church of England was a key secular (as well as religious) institution until the Victorian period. As part of local government, it was responsible for poor relief, running local charities, and even local roads and law enforcement. As a result, the 'parish chest' contains a lot more than just the registers of christenings, marriages and burials. Their registers also often contain records of adherents to other (non-C of E ) religions.
A Church Near You - a church search facility that in many cases gives maps with current Church of England parish boundaries.
The Primitive Methodist church was an early 19th century (1807) secession from the Wesleyan Methodist church and was particularly successful in evangelising agricultural and industrial communities at open air meetings. In 1932, the Primitive, Wesleyan and the United Methodists joined together to form the Methodist Church in Britain. Their website provides a brief history of Methodism and advice on research.
In 1972, the Presbyterian Church joined the Congregationalists (see above) and others to form the United Reform Church. They were influenced by Calvinism which rejected bishops and believed that the church should be governed by their ministers and members.