Hey Cra-Z.
Yeah, the work visa sitch is tough. Sorry. Not everyone gets a work visa however, and I’ve known Americans/Canucks/Aussies to have stayed in Spain for years at a time, working and living illegally, so there is some hope if that’s what you want to do. You only have 90 days with your Canadian passport, but with the EU countries’ border agreement you can stretch that out if you know what to say.
Being 18 I think the best chance you might have to find work is to work at a bar. To do that you’d definitely need to be in a heavily touristed area or speak Spanish. Do you speak Spanish? That’d help. Knowing French might help you to learn faster too… Location matters a lot. Where’s she going to be moving to?
Not to be discouraging either, but there’s a lot of age discrimination in Spain. It’s a traditional type of place, keep that in mind.
Wages are low, but so is the cost of living. You’d probably be able to make enough to live, but not enough to save.
If you’re really dedicated to following your girlfriend to Spain however, keep up hope and you can make it work. Check out the info on this site. There’s a lot about teaching English (although again, your age might be a hurdle), visas, cost of living, etc. that will help you figure out if this is the right decision for you.