Now it is Ok for Great Briton and Canada to have an official religion, even though it was started by some dude King Henry IIIV who just wanted to get a divorce? Now that is a reason for having an official religion. Tradition is not always good, I can see keeping the monarchy around, that is who you were and is history. What do you mean the Church of England has not done you any harm, how many Catholics died because Henry wanted a divorce, in both Great Briton and Ireland. It is like our slavery and just as bad, something that must be put behind you.
Canada does not have an official religion, Britain does. And regardless of what was done in the past, having an official religion is not harming anybody in Britain today. Britain is as tolerant of other religions, of minorities as any other democracy, perhaps even more so than USA. Thus Britain has civil union for gays, Britain legalized homosexuality in 1965, there are parts of USA which would like to recriminalize homosexuality, if the Courts would let them.
Official religion is just a tradition, like the monarchy. Church of England does not get any favored status with the government, money from the government etc. for being the official religion. Also, I am not aware of any grassroots movement which wants to delist Church of England as official religion.
So again, if it ain't broke, don't fix it.