If your business requires you to visit the UK regularly over a longer period, you can apply for a visa that lasts two, five, or ten years. However, you can only stay for a maximum of six months on each visit. Academics coming to the UK on a sabbatical or exchange arrangement can apply for either 6 months or 12 months, subject to meeting the requirements. A senior doctor or dentist can also come to take part in research, teach or undertake clinical practice (as long as it is not a permanent position) It is recommended that the visa application is prepared diligently because at times, visas are getting refused for even a small error.