I am in the same boat right now, will be in the KW area for the summer for school. As far as I know (and I have been looking for a while) there are no MMA schools.
For BJJ there is Dragan Alliance in Kitchener (http://www.alliancebjj.ca/dragan.html). That is where I will be going to train and have heard great things about that place, and their students usually do fairly well in tournaments.
There is a Muay Thai Club (TKO Fighting Arts) that shares the same place that Dragan Alliance uses (different fees though, www.tkofa.on.ca)
Also there is Phady's Muay Thai Club in Cambridge (http://www.phadymuaythai.com). Do not know anything about this club but have heard that it is pretty good.
Hope this helps, and if you find any others in the area that I missed please send me a msg because I have been looking.