You can't just say you want to get into "advertising", there is a whole world of functions that deal with advertising, especially at an ad agency. If you want to go into the creative side and create ads, its going to take you a while to reach that position. If you want to manage ad accounts for companies, even longer. Usually when you start out, you are a buyer who purchases air time for your agency's accounts. I'm not in advertising, I'm in marketing, but seeing that advertising is a sub-function of marketing used to facilitate a message in the marketing strategy, its important for me to understand its being. Also, my cousin works at an ad agency in Los Angeles and has exposed me to some areas of the business (he whent to UNC, haha)
Just do some research on some brands and see if they outsource the ad creations to an agency, or produce them in-house. That should answer the question as to where you should work; a fashion house, or an ad agency.
The studies you are doing will set you up nicely for a career in the advertising industry, just take advantage of internships and see what it is that you want to do in advertising.