L visa to X visa

I just want to make sure about one more thing...I am getting a L visa for travelling to Guangdong (for 2 weeks), but actually I plan to study in Shanghai for six months instead. I can't get the x visa though because by the time the academic papers reach me I will probably be in China already. So do you reckon the university can convert the L visa into X visa for me, or do I need to get back to the UK and apply for the student one? Thanks.