The need for visa and approved period of stay vary greatly depending on the applicant’s nationality, visit purpose, and period of stay. The short-term visitor visa does not allow multiple entries even if you leave the UK before the visa expires. If you need to stay for over six months, you should obtain a long-term visitor visa (from one to up to ten years) in your normal country of residence before your departure.
To get a long-term visitor visa, you should satisfy the requirements for the visa you apply for. For example, you should prove your expertise in a field of specialization in order to get an Academic Visitor Visa (up to 12 months).
