A UK PPL is fine you'll need a foreign licence validation from Transport Canada (Canadian CAA) at a cost of 40 Canadian Dollars (I think). It takes about 45 minutes to arrange if you drop by one of their offices and lasts for a year. A Canadian Limited Time PPL can be obtained which lasts for 3 months I think and is slightly cheaper.
As for areas to fly, I did mine out West. I rented an IFR C-172 (I) from an outfit in the Fraser Valley near Vancouver (£43ph wet on average) and toured through the Canadian Rockies and Prairies.
You can get a Canadian PPL issued on the basis of your CAA/JAA PPL if you sit the PSTAR (Airlaw) exam and pay Transport Canada 55 Canadian Dollars. You will also need evidence of your 150nm qualifying cross-country route (take a CAA chart).
As mentioned above you need an ICAO Medical (UK class 3 is ok). If you intend to try and gain a Canadian PPL, you will either need the original medical form your doctor filled out before granting a class 3 or you'll be obliged to do a Canadian Medical (approx 100 Canadian). Getting a Canadian PPL can be a pain but it’s a nice way to finish off if you intend going back on a regular basis.
Apart from that have fun it's a beautiful country and if you fly out West you'll learn a lot about mountain flying.
Cheers
GF