transferring uni

I currently go to a UK uni and its my first year however I want to transfer to either UBC or McGill for fall 2027. Was wonderig how application process would go, am I at a disadvantage in getting accepted since high university grades are hard to achieve or will they assess my high school grades more?

It also mentioned that they assess my application depending on how transferrable my credits are but I only know my full year of uk credits will be 120 credits.

Also would I have to rewrite a personal statement etc or the application is completely different