http://www.ukba.homeoffice.gov.uk/visas ... g/general/

А разве в Англию американцам нужна виза?
или вы еще с гринкарт
U.S. citizens are generally allowed to travel to the U.K. without a visa if they are coming only for tourism and only for a short time. However, the decision on admission to the U.K. is made by British authorities (the UK Border Agency – UKBA) in accordance with British law. Under British law, some common activities may not be considered “tourism.” Religious volunteers, charity workers, interns, prospective students and others pursuing special programs may need to get a visa before traveling to the U.K. You can find more information on U.K. visas and application procedures on the UKBA website. You can also find information about traveling to the U.K. on the Department of State’s Country Specific Information page.

американцам не нужна виза в англию

делайте заранее, знаю что у них волокита на это дело