It’s a very good place to start (cue Julie Andrews), you need to know if you can build a laneway house.
What does the city say?
Well, you can go to this site and see what the city says. There are restrictions (I may have mentioned those before) but you can link to and download the laneway-housing-howto-guide.
And that is a handy thing to have as you start your adventure. I read it and re-read it about fifty times when we started talking about building our own.