Can I apply for Tier Student 4 visa in-country due to Covid-19?
If you have existing Tier 4 leave, you can apply in-country for Tier 4 student leave providing you do this before you current leave expires, or by 31st August if your leave expires before then and you were granted an extension. The course start date on CAS must be no later than 31st December.
Switching into the Tier-4 route from some other routes including student and visit visa will be allowed on an exceptional basis up to 1 October 2020 when this will be reviewed. To benefit from the provision, you must have arrived in the UK before 31 July 2020.