Organisations with ownership and care of churches in Essex, Norfolk and Suffolk
most sites below feature maps, contact details and links to websites of individual churches

Anglicans (Church of England)
A Church Near You (contact details for churches in England and Wales)
Diocese of Chelmsford (all of Essex)
Diocese of Ely (south-west Norfolk and Cambridgeshire)
Diocese of Norwich (the rest of Norfolk and north-east Suffolk)
Diocese of St Edmundsbury and Ipswich (the rest of Suffolk)

Catholics
Diocese of Brentwood (Essex)
Diocese of East Anglia (Norfolk, Suffolk and Cambridgeshire)

other significant denominations in Norfolk & Suffolk (national sites)
Methodist Church
Baptist Union
United Reformed Church
Grace Baptist movement
Unitarians

other agencies
Churches Conservation Trust (about fifty redundant churches in the two counties)
Friends of Friendless Churches
Norfolk Churches Trust
Suffolk Churches Trust
Ipswich Historic Churches Trust
Norwich Historic Churches Trust

Please feel free to recommend a site.