I've got lots of British and American channels at home, so I know how fast native speakers can speak. I don't think native speakers try to speak more slowly when doing interviews, for example. Right?
I think I'm prepared for the speed and pronunciation. I'm not sure that I'm ready for slang and things like that. When I was in Enland last summer I talked with lots of British teenagers but it was very, very hard for me to understand them - because of slang they constantly used. By the end of my stay in the UK I even got used to their speed but I still couldn't undestand many of their sentences. In my opinion, it's impossible to learn to understand slang in 4 weeks. I also think that it's useless trying to study slang words or expressions at home as my head doesn't usually keep them for a long time. I've got to constantly try them out on somebody. Otherwise, I forget them very quickly. I'm not keeping to the topic anymore
BTW, where do you live in Canada?