Try using the information from this link
http://www.dh.gov.uk/en/Healthcare/E...able/DH_074376
"Am I entitled to access primary care services?
Any person living here lawfully and on a settled basis is regarded as resident in the UK and therefore entitled to free primary medical services. On taking up residence in the UK it is advisable to approach a GP practice and apply to register onto its list of NHS patients. The practice may choose to accept or decline your application. An application may be refused if the practice has reasonable grounds for doing so, such as if you are living outside their practice area. A practice would not be able to refuse your application on the grounds of race, gender, social class, age, religion, sexual orientation, appearance, disability or medical condition."
A fiancee visa may only be for 6 months but it is a settlement visa and the holder is taking up residence in the UK.
