This was years ago and I have actually now driven in the UK myself. Yes, I'm sure overall I'd be less likely to die if I were driving every day in the UK vs driving every day in Canada.
But let me tell you, the first day driving on the other side of the road is a real doozy. And I nearly died a couple of times. And I was doing my very best to avoid "magic roundabouts".
(I actually drove all week through rural Wales, which was a different kind of adventure)
(And Canada is already among the safest non-European countries, with significantly fewer fatalities compared to the USA)