I'm actually in a similar situation, booked with Aeroplan, for a redemption in first, except the difference is I have a 20 hour layover and it's this week! (???-MCT-LHR withholding exactly iteneratry and dates for privacy)

I was planning on requesting at the primeclass lounge for a room (found an article from early 2022 of someone who was able to sleep 6 hours there by just making a deal for using their priority pass card with some negotiating, but may prove to be unreliable) otherwise I was going to use the business class room to sleep, seems good enough for me since I've allotted long hotel stays on both of my other ends of my journey.

I can report on the first class lounge hours etc, and also on if i was able to get 6 hours in the primeclass lounge, as well as the overall sleeping situation. If you have any other questions I can try to answer from my experience this week!