From the UK a flight to Canada is considered long haul and competition is less available to drive down prices as can be found in the short haul market. That said good online travel sites like expedia can help as well as farecompare or travelsupermarket
One can buy cheap or low-cost flight tickets from the Indian Eagle website
Expedia, Orbitz, Travelocity and Priceline are probably the most common online sources where people look for cheap flight tickets. The website Fare Compare is another source to use when looking for cheap flight tickets.
tickmaster.com or ticketmaster.ca depending if you want tickets in Canada or the USA and they are only cheap if you want crappy seats
The best time is Tuesdays, and 4 weeks before your flight.
I have heard the sooner you buy the tickets in advance the cheaper your can get the tickets. But I do know of a cheap website to buy airline tickets online at: www.orbitz.com.
One can buy cheap Eurorail tickets from the official website of EURail. One can also buy cheap Eurorail tickets from websites like Rail Europe, Rick Steves and Travel student.
There are many different websites where plane tickets can be purchased. What is the cheapest site for one flight may not be the cheapest for a different flight, so it is necessary to compare each flight. Some sites to compare pricing are: expedia.com, southwest.com, cheapoair.com and travelocity.com.
Cheap tickets for the holiday can be purchased at many different airlines. Some of the airlines that has cheap tickets is Delta, America, United and Northwest.
There are a lot of places where cheap group airline tickets are available online. airgorilla.com and travelocity.com are just a couple of good locations to get cheap airline tickets.
Airplane prices are rising, so try finding the cheapest airplane tickets that you can find as quickly as possible. Airplane tickets will only grow as the prices for oil and gas grow as well, so I wouldn't wait and buy the cheapest you've found.
On the internet.
There are tons of places on line to help you find cheap airline tickets, i would check out Expedia.com, they seriously have the best deals and can help you with what you need