Hey ABFLYER,
Unless you fly a CDN registered aeroplane you need to have the UK CPL/FATPL or the JAA CPL/FATPL.
I would talk directly to companies who are specialized doing this like OATS, Bristol, Bournemouth, Horizon etc. Just look through the classifieds of Flight International.
I assume that all you get for your Canadian License is a PPL.
You can do the JAA ATPL Theory on a fixed budget. You have to figure out how much flight training (real flying) you have to do.
I am starting my conversion at Horizon. If you primary goal is to fly in the UK it could make more sense for you to do your conversion in the UK, and start making contacts.