I had a fantastic experience flying in Canada. If you are looking to fly in Canada to save money converting back in the UK then these are my views. Converting the CPL back here in the UK was straight forward and to the discretion of the training provider. I think it took 5 hours 7 including test. This made it a financial benefit. The instructor conversion I haven't done but understand it is half the full course. This means you can gain a canadian and JAA for the same price as just a JAA licence. Theory side however you will need to re-do the whole ATPL theory which is much harder than the Canadian equivalent.
IR side you will have to re-do the whole thing to "convert" to a JAA. There is a 5 hour reduction as you already hold a commercial licence. This rule kicked in about this time last year. So don't take the IR in Canada if you are looking to save pennies. Worth doing the ME to as again this conversion is left to the discretion of the training provider. I just took the test with no additional training so that saved a few quid too.
Hour building is obviously cheaper than the UK too. I had a great time flying to various places in Canada and the US. Encountering extreme weather and conditions and all kinds of airports from tiny to huge internationals that you wouldn't be able to go to in the UK.
You do need to fly a bit in europe too to help speed up the RT as the airspace is more congested.
Hope that helps a bit and have a great time.