Average entrance average for Engineering in 2009 in the top Canadian Engineering schools
University of Waterloo- 89.2%
Univeristy of Toronto- 90.3%
Universty of Alberta- 87%
Other less reputable schools have averages in high 70ies or low 80ies
I admire your thought process that led you into considering taking a term off,
Have you considered taking the summer off instead ?
that will be exactly what you need, a few months off to do what you want and in case it wasnt a good idea, then no harm done..
Assuming that your normal...
I think an extra year for double degree is not too long, considering some people have to do 2 years extra...
Anyway if you decide to do only one, its more practical to do it in Computer Science and then minor in maths.
I would vote JAVA if your programming knowledge is non-existant..
Because you need to be exposed to some sort of programming at some point, to understand how the computers 'think'... besides it opens a multitude of opportunities, you might fall in love with it and switch majors or decide to...