Extending a tourist visa

[DhavalS93]

I am appearing for Overseas dental registration exams in the UK. I am currently on a tourist visa of 6 months which expires in Jan 2017. I wanted to extend it but found out on the official website that extending would be just for 3 months and that too its ridiculously expensive (811 pounds). So decided to apply for a new tourist visa now. Can I apply for a new tourist visa while I am currently on one? Or is there any other way around this situation that you guys can think of? Do let me know. Thanks!

[daggit]

Generally speaking, you cannot apply for a visa of a country you're already in. For US visas, you must apply outside the US, and I reckon that's true for the UK as well.