Heya man, I am currently at Falmouth and on my first year of creative advertising. Whilst I myself did not bring a portfolio. I had a couple of youtube links of my previous film work on youtube so I just used that instead.
Basically if you have work you are proud of you should bring it along! And the main thing that "wowed" them at the interviews was the fact I had made TV advertisements for previous projects. So if you have any print advertisements or films from a previous course make sure to prioritise those over other bits of work.
Basically they try to judge you on your creativity more than anything else. So just make sure to bring what you think is good work and if you do have work from advertising in the past make sure to bring that along too.
Just make sure you get what you want out of the interview, ask them whatever you like. Since apparently I got in to the course mainly because of my enthusiasm and passion for the subject.
Best of luck friend!