As of now the UK is not accredited in Canada. After completing the program you would have to complete a 2-3 year qualifying program in Canada (tough to get into) or else complete the NDEB equivilency process (~10% pass rate). I'd recommend only attending a school accredited in Canada because otherwise there is no guarantee that you will ever be licensed in Canada.
Dental school in the UK is different than in the US or Canada, it's taken directly after sixth form and leads to the BDS degree. In the US and Canada you go to college first then enroll in a program leading to DMD or DDS. I would be very surprised if you found somewhere that would let you transfer between the two systems.
I think it would be almost impossible to transfer. However, you are lucky, because Canada accepts credentials from dental schools not only from the U.S. but Australia, New Zealand and now Ireland.
Study at any of those countries before UK, it will save you a ton of time, money, and work.