There's an absolute ton of info to be had by trawling through the wiki and forums of British Expats:

http://britishexpats.com/forum/forumdisplay.php?f=33

Last I checked it was taking around 9 months if you could make your skillset fit in to one of their priority job classes where Canada is experiencing skill shortages. It's much quicker to get a temporary work permit if you can find an employer to sponsor you, and then apply for residency once you're here (which is what i'm doing).