If you are coming to the UK to study for a period that is less than six months (11 months for English language students) you may be able to apply for a visa as a Student Visitor. You should note, however, that if you are a Student Visitor you will be granted a visa for a maximum of 6 or 11 months. This cannot be extended and you cannot switch into any other immigration categories from inside the UK.
Although entry clearance may be an option for non-visa nationals, if you are planning to come to the UK as a Student Visitor, even for up to 6 months, you should apply for entry clearance as a Student Visitor in your home country to avoid any immigration problems occurring when you enter the UK.
If you are a non-visa national, and decide not to apply for entry clearance, you need to ensure that you present your Student Visitor visa letter to the immigration officer at the port of entry and specifically ask for a Student Visitor visa. You need to ensure that the letters 'VST' appear on the stamp.
The immigration conditions relating to a Student Visitor are very restrictive. Student Visitors are not allowed to remain in the UK once they have completed their course and cannot work part-time whilst studying in the UK. If you are planning to continue studying for longer than six months then you should apply for entry clearance as a Tier 4 General student and not as a Student Visitor.
Further information and guidance can be found on the UKBA website.