wire:
Sounds easy but it is not quite like that.
You cannot get a a provisional CDL license unless you have passed the written class one and air brake tests and and have also turned in your UK driving license for a Canadian class 5. (car license.)
As far as I remember you need actual status in Canada such as a legitimate work permit to do this.
Also you would be taking a risk by actually seeking employment while visiting Canada as a tourist as that would make you liable to get deported if you were caught although getting caught is probably unlikely. Certainly you would not want to have any incriminating documents on you when you checked in at the arrival terminal at the airport such as a resume or references as you could be turned around and refused entry to Canada.
The new minimum entry level training (MELT) requirements means that the truck driving license training now takes around 6 weeks and costs around $10,000 unfortunately.
This training program varies slightly from province to province but is mandatory by law and is required by everyone regardless of whether you already held a truck driving license in another country previously.
I see your location is Manitoba, exactly the province I had in mind 
I wasn’t aware it was illegal to job hunt while in Canada, not quite sure what the difference is between doing it from home or from inside the country but the law is the law I guess. As for the MELT cost, that’ll probably translate into less wannabetruckers due to the crazy high entry costs.
So if you can’t get your CDL until you have a work permit, I’m guessing the only option is to secure a job first? This seems like it’s going to be a bit awkward, both for the employer and for the immigrant but I’m guessing if you have 10 years of experience driving Class 1’s in the UK the employer is probably going to be very confident you’ll pass your CDL if they do take you on.