To locate a prison you can in the U.K you can search via the National Offender Management Service (NOMS) Prison Finder or use the NOMS Prison Map. The website allows you to search and find any prison in England and Wales, by name, category or area. Information provided includes contact details, capacity, regime and visiting information. There are also recommendations about how to travel to each prison.
Prison Finder: http://www.justice.gov.uk/contacts/prison-finder
Prison Map: http://www.justice.gov.uk/downloads/contacts/hmps/prison-finder/prison-map.pdf