You could use it for a while (exactly how long is difficult to say, as things tend to change too much too quickly here and the regs may be different by the time you come back) before needing to apply for a UK issued EASA licence. However, currently you'd need 100 hours in order to do so, plus a few writtens and a flight test. If you came back before you finished the Canadian licence, currently none of the hours would count................