Most overseas airports also provide similar information. (The major is exception is the USA, which has some of the world's worst airport websites). If you want to consider connecting via one of the Canadian airports served from Manchester, you'll need this list:
http://www.admtl.com/...ionsServedCanada.aspx
To plan connections via the USA, you'll need this:
http://www.admtl.com/...rvedUnitedStates.aspx
To connect via another route (e.g. Heathrow or Amsterdam), this should help:
http://www.admtl.com/...vedInternational.aspx
I've not researched specific connections but my first thoughts, looking at those links, are that you should consider travelling via Amsterdam (because KLM fly both legs, so through ticketing should be available) or via Toronto (because it has very frequent flights to/from Montreal, with a flight time of just 1 hour 20 minutes).
Chris