This really does depend on the type of visa that is being applied for. There are various types of visas such as a visitor, student, worker, marriage and so on. It will also depend if the applicant is able to meet the eligibility and suitability requirements of the Immigration rules. For more information, explore here:

Original Source: https://www.quora.com/How-can-a-Turkish-guy-move-to-the-UK/answer/My-Legal-Services-1