I just bought my first house. It doesn't have a garage, only a driveway. I live in Canada.
My cars are a 2014 sedan and a 2015 suv. I use them everyday.
Do I NEED a block heater for January-February?
It depends on the how cold it gets where you live in Canada, but usually it would be a sane idea to have one. I lived in the north-west corner of Montana growing up. It would normally reach below freezing, but above 0°F (-17°C) most of the winter nights. Only when the forecast was to be below this would we "plug our cars in" for the night.
As long as your anti-freeze is in good shape, your vehicle can handle being this cold without issue. 50% antifreeze (mixed with 50% distilled water) is good down to about -34°F (-37°C), while 70% antifreeze (mixed with 30% distilled water) is good down to about -82°F (-63°C) (NOTE: These numbers do depend on what type of antifreeze is being used ... these are basic numbers for the "green stuff".)
If using this amount of antifreeze, the real issue is not whether your block will crack due to hydraulic expansion, but rather that your engine oil will not flow very fast, so you have oil starvation on key components of your engine. This will cause large amounts of wear until the oil starts to flow properly. Using a block heater in these situations is imperative so that the oil will flow properly from startup.
I also live in Canada, southwestern part. I would suggest simply paying attention to the weather / forecast. If it is going to be below -10C, be prepared to plug in. Vehicles will probably start down to the -20C's, but cold starts are damaging. Probably need to watch the weather more than January and February depending where you live.