Will any hours and exams taken here count toward my continuing studies in either Aus or UK or will I effectively have to start again when I finally make the move?
I would suggest that if you do start in Canada that you get every single log book entry for training undertaken - signed by the Instructor with his certificate number.
Your hours would be ICAO compliant and so would count if you then transfer to another ICAO country. Personally, I would not suggest that you do any written exam(s) in Canada - unless they are mandated to allow you to solo (sorry I do not know Canadian regs). If you were to go back to the UK, you would have to take all 7 of the CAA Private Pilot written exams regardless of any prior completed Canadian exam(s). I assume that the same applies with CASA.