Home Office Visa:

All people entering the United Kingdom must have a passport and other travel documents valid for the UK.  In addition, certain nationals will require visas and this will need to be checked with the appropriate British representative prior to travel to this country.

See the British Home Office home page for further information. The Immigration & Nationality Depepartment deals with visas.

Permit Free Training (PFT):

For doctors engaging in basic specialist or general professional training or who hold appointments in the SHO grade or equivalent, there is an initial grant of time not exceeding three years with provision for extension of this period: however there is an aggregated maximum limit of four years PFT.

For doctors who qualify for Higher Specialist Training (HST) or who hold appointments in the Specialist Registrar Grade or its equivalent, there is an initial grant of not exceeding three years and the provision of a further extension of stay each not exceeding three years, depending on the requirements of their training programme. Doctors in non-training posts will require a permit.

See Immigration and Employment of Overseas Medical and Dental Students, Doctors and Dentists in the UK, NHS Executive HSG (97) N.18. (Full text of document available).