You need short term study visa if you will be studying in the UK for six months or less or up to 11 months long for English language courses.
You can apply for short term study visa if do a short course of study in the UK, such as an English language course or a training course, or do a short period of research as part of a degree course if you are studying abroad.
Studying for six months or less
Apply for Short-term Study Visa
You can apply for a short-term study visa if you want to study short course of study in the UK –
You can apply for a visa up to 3 months before your date of travel to the UK.