Yes, you should be able to exchange your Canadian licence for a UK one without taking the tests.
According to this webpage:
https://www.gov.uk/exchange-a-foreign-driving-licence/y/yes/car_motorcycle/des/can, you have 5 years to exchange the Canadian licence, providing it is still valid, and it will cost you £50.
However, it also says you will only be legally licenced to drive automatic cars, so if you wanted to be able to drive manual cars, you would need to take the UK manual driving tests.
If you didn't have a Canadian licence and only had a US one, you would not be able to exchange your licence for a UK one and would have to take all the tests to be able to drive after 12 months in the UK (this is because the US has no reciprocal exchange agreement with the UK, but Canada does).