The UK National Archives guides cover censuses, migration, military records and repositories. Start with the topic guide, then the Discovery catalogue: a description identifies a record but does not guarantee free online access.
The official guide explains using the General Register Office for family history in England and Wales. Identify an index entry, compare known details and check the ordering options available for that record.
Northern Ireland’s public archives offer family and local history applications: probate indexes, maps, valuation books and directories. Choose by place and event; this service is distinct from Republic of Ireland archives.
Dates below apply to each resource, not an exhaustive check of its collections. Read the limits and official pages before requesting records or visiting.