You've picked three games that will sell out almost instantly.
The Habs haven't been to Western Canada since early 2006, the Nucks are always a big draw in Calgary, and not only is it the Battle of Alberta, but HDiC, so that'll be a tough one too.
Keep an eye on here, and the teams' websites for specific on sale date information. I don't know if being in the UK will help or hurt your chances of getting through on ticketmaster.ca.
Consider yourself lucky if you're able to pick up tickets to even one of the games through the official channels, for face value. Keep in mind that all three teams have large season ticket bases, so only a limited number of tickets ever even get released to the public.
You should probably plan to have to go to the secondary market (scalpers) to get your tickets. Stubhub.com is probably your best bet (and one that ensures you don't have to deal face-to-face with slimy scalpers) for buying tickets on the secondary market. You will likely have to pay more (possibly much more) than face value for the tickets, but if you want to go to the game, it's what you'll have to do.
There's also the possibility of contacting each team's PR department directly, explaining your situation and seeing if they can help you acquire tickets for the games. Also, post here (and the other team's message boards, if you can stomach it) asking if anyone is willing to sell you tickets to those games to help a couple of guys from the UK see their first live NHL games.
Turn up the good, turn down the suck!