with drawing your student visa application...

What happens if you want to withdrawal your tier 4 application a few days after sending it?... my girl friend applied for a course in Uni and got a visa letter to extend her student visa... After joining afew days

ago, she has realised the course does not meet her needs and she no longer want to continue with the course and visa extension..... She is planning to leave the country but she does know if the home office

will need to interview her fast... She is currently waiting for the acknowledge letter from the H.O but she doe's not want to attend classes again.... will this affect her future visa application in future?

What is the time limit for withdrawing an application?.. does she still need to be taken biometrics?.... does she still need to inform the home office if she is not atending classes anymore?