Working as a Lecturer / Assistant Professor in UK vs Canada
I do not know exact details of the UK system but I have colleagues there so at least I have some general idea of the UK system.  My impressions of Quebec come from doing grant committee work for the provincial government.
In Quebec the dominant language is French: it may or may not be a requirement to learn it but if you don’t you’d miss out on much the vibrant cultural scene.  Quebec also runs a French-inspired system of education (unlike English Canada, which is much closer to a US-based system): I don’t understand the UK system well enough to compare, but salaries are lower than the rest of Canada (although the prestige is greater).  The provincial tax burden is not light (although it’s not the horror stories you read compared with other provinces, except Alberta), but the quality of live is quite high: you can expect to have the means of buying a house within 5 years of your appointment (something not so clear if you are appointed in Toronto or Vancouver).
Quebec is culturally more creative than the rest of Canada: the joke is that the graduating theatre class in Quebec always puts on a new play at graduation, whereas the graduating class in Ontario always puts on a Shakespeare play.   This creative drive trickles to the research level: there are more funding opportunities in Quebec (the provincial government runs its own funding scheme, on top of all federal scheme).  Tuition is low compared with other provinces: it is a very attractive research environment, and many in other provinces are quite jealous of the additional government funding opportunities.
Of course there is “true” tenure.
My sense is that the UK is much much more complicated.  Quebec universities do not run on full-cost accounting (I know some UK universities do) so the paperwork required in applying for and managing grants is an order of magnitude lower than what I’ve seen in the UK.  Many federal grants are individual grants (there are also some team grants and some industry grants) and these individual grants are very flexible, with minimal oversight and simple rules (v.g. no business class flights).  If you use this $$ poorly (nothing to show for it at the end of the grant period) nobody will care but you’re unlikely to have a strong enough file to get your grant renewed: by and large the system works reasonably well.  Overall, my sense is that the Canadian and Quebec systems are much less business-like and penny-pinching than the UK system.  “Big grants” aren’t so frequent: the Canadian system tends to distribute its resources over individual researchers rather than concentrate resources in a few big centers.
I do not know what you have in mind, but - say - McGill is not called the Harvard of the North for nothing.  It has a history of excellent research: I don’t know about biomedicine but I know that there’s a lot of hospital-based research there (same as UK as far as I know).
Side note: I have a colleague who took a job in the UK and came back to Canada simply because the funding environment in the UK was so much more restrictive compared to the Canadian system.  I suppose this is anecdotal but it does align with my own experience with the UK system (through international team grants).
Nota: you can check funding levels for federal (NSERC) grants here: https://www.nserc-crsng.gc.ca/ase-oro/index_eng.asp
Public employees salaries in Quebec are not public but they are in Ontario (if you make over $100k).  Faculty salaries in Quebec are lower than Ontario and I do not know the x factor between the two, although I would guess ~0.8. You can get some of the public sector salaries in Ontario from this link.
You might have to download some stuff to search by university or sector.
Montreal has an excellent public transport system (including subway, with subway stops at all major universities).
My impression is that teaching loads are quite acceptable.