Tier 4 (General) Student Visa
This visa is for a person who among other things is 16 years old or older, who has an offer of a place on a course with an accredited UK organisation, knows English and can support themselves financially.
You would need the reference number also known as “confirmation of acceptance for studies” (CAS), which you would enter on your visa application.
You would also need to submit such documents as ID, financial evidence, consent of legal guardian if under 18 and medical results of a tuberculosis exam in certain instances.
You can extend this visa to continue the course if you still fulfil the requirements, however you cannot spend more than 5 years in the UK studying (with certain exceptions).
You can also switch to this category from certain other visa categories.