On the
UK end the most important things to do are file a P85 with HMRC to declare non-residency and file an R105 with your bank so they stop withholding income tax from your bank interest (you have to declare this on your T1 and pay Canadian income tax).
In addition I highly recommend making voluntary National Insurance contributions if you qualify (three years minimum of contributions). If you work in Canada, you qualify for Class 2 contributions which are only around £9 a month (HMRC do it by direct debit). When you turn 65, you qualify for a full
UK pension, which at the moment is around £6,700 a year. The only problem is that you don't qualify for cost of living adjustments if you reside in Canada. You have to have 30 years worth of contributions to get the full pension, but 9x12x30 = £3,240 so essentially you get all your money back in the first six months of being on a pension! It's a bit of a loophole in the NI system because Class 2 is usually for self-employed people and Class 3 is for non-residents, but employed non-residents are treated as Class 2.
On the Canadian end the most important things you need are your passport and complete CBSA forms B4 and B4A. Go to the Federal building when you get here and apply for a SIN. In most Provinces you can swap a
UK DL for a provincial one and register for healthcare. That's pretty much it.
Steve.