One of your class mates told me about this site of Multilinkual in Madrid, which is a group of Spanish and people from other nationalities who meet to exchange conversation.
On Internet I've found this site with information about conversation exchange. In this page there is an interesting section in Resources related to survival phrases. Have a look.
In Alcalá I think there are some other places to exchange conversation, but it's a bit difficult to find them for free, without paying. If someone knows any place, let me know and I'll write it down in the blog for all of you.
See you in class