Hi, and welcome to the forum.

I'm hoping someone will drop in who has some experience in this area. My sense is that visa categories haven't quite caught up with the phenomenon of telecommuting over the Internet and you may have some difficulty conveying to the Canadian immigration folks exactly what your working status is.

If you're working for a company that pays you to telecommute, you may want to ask them what, if anything, they will do differently if you move to Canada. There is no point in their paying into the UK national insurance scheme as you won't be able to make use of the benefits - other than perhaps retirement. Do they make the same sorts of payments to the Canadian national insurance schemes? Or are you working as a contractor, paying your own taxes and insurances on your own? That could require a different work status altogether in Canada.
Cheers,
Bev