How can I choose between my dream career and what my parents want?

I really want to study Fashion Design when I go to University. I’m really passionate about this subject and would love to have it as a career. But my parents totally oppose this, they want me to work from home and start my own fashion business from home but if I don’t know much about fashion how am I supposed to do this? I am studying fashion as a BTEC in college. They won’t allow me to go to a University even if it is just near me. They haven’t even let me go out even once by myself or with my friends, and this is why I get nervous when talking to strangers. I understand their worry about my safety but I feel this is too much overprotectiveness. I want to study in Korea (I’m in the UK), mainly because my subject is fashion, and the fashion industry there is constantly developing. I’m too nervous to even tell my parents I want to study abroad. I haven’t even worked once! I know I’m going to be 18 and I can make my own decisions but it really isn’t all about independancy in my culture. Please help me on what I should do.