When to apply if you are switching to a Student Visa from within the UK
If you are in the UK, the date of your application for a Student Visa must satisfy a number of requirements.
The date of the application must be within 6 months of getting a Confirmation of Acceptance for Studies and within 3 months before your course starts.
Of course, you must apply before your current permission to remain in the UK expires. If you apply from within the UK and at the date of the application your permission to remain has expired, your application will be refused for not meeting the suitability requirements, as you would be in the UK in breach of immigration laws.
Your course must begin with 28 days of your current visa expiring. If your course begins more than 28 days after your current visa expires, you must leave the UK and apply from outside.
You can stay in the UK until you get the decision on your Student Visa application or on the administrative review, if your application was refused.
If you want to apply for a Student Visa and need specialist advice, feel free to contact me. Please note that I am an accredited immigration adviser, not an employee of the UK Visas and Immigration. I charge fees for the advice provided.