Wow you have left it incredibly late for travel for such a life-changing event. I do hope everything works out for you and your new family. @Stuart275
Just because you can book now, doesn't mean your travel can't get cancelled closer to the date or your accommodation @Stuart275 if Canada shuts its border to UK arrivals.
I would imagine hosts would be happy to accept a booking to a self-contained place if you are able to get there.
However have you thought about the health implications for the baby you are travelling to adopt. Are you saying you would self-isolate and get tested before meeting him/her.
I would travel ASAP and not wait to the weekend if you are worried about Canada imposing a ban on travel from the UK.