According to
an old local article about it, the practice arena will be at the Western Fair Sports Centre which appears to be not too far east of downtown. However, so far
the Worlds 2013 website FAQ only says that "all practices taking place in the John Labatt Centre" are included with all-event tickets and doesn't say anything about the practice arena at all whereas the home page says "access to all practices". It looks like it should be easy to get to on bus routes if they do open it up.
I also found
a downtown London guide with a link to a PDF file of a lovely map (look for the yellow box) with hotels, shopping, restaurants, parking, and even WiFi hotspots marked on it. Speaking of which, I've been "walking" around the area using Google street view as previously suggested and I have to ask: has
anyone been able to figure out precisely where that Hotel Metro is?

Is it in the middle of the market?
Anyway, I figure that I should report in that I bought tickets at 10 am on the first day of regular all-event sales, by internet, and I got row R.