In short, to apply to adopt a child you will need to go through an adoption agency.
Some agencies are voluntary organisations – for more information see the website of Consortium of Voluntary Adoption Agencies.
Most adoption agencies are, however, part of the local authority children’s services or social services departments of local authorities.
People are not limited to their own immediate locality but most agencies will work within a 50-mile radius of their office. Although it is only possible to follow through with an application with one agency, several can be contacted at an early stage and many will offer you the opportunity to attend an informal meeting with a social worker before you decide to make any formal application.