Applying for/extending a Student Route visa in the UK

• How do I make my Student Route visa application?
• What is the time cap on study in the UK?
• My visa expires more than one month before the start of the course I want to study
• Can I apply for a Student Route visa from inside the UK whilst on a different visa type?
• Will I need to attend an interview if I apply for a visa in the UK?
• I have a Student Route visa and I need to apply for a course extension to the maximum period of registration. Will this affect my visa?
• I have a Student Route visa and I need to apply for an extension to my dissertation or corrected thesis/revised thesis deadline. Will this affect my visa?