Allan, re your plans for this summer... Last summer, a friend was on the same WestJet routing in reverse and this "milk run" was totally exhausting with the layovers. On the outbound flight, she was on the B787 Dreamliner YYC to LGW. In hindsight, she wished she had booked her return from Glasgow to London, and then non-stop LGW-YYC on the Dreamliner.
If I were you, I would get on top of your flight arrangements with WestJet before they get back to you. (I say this from a recent WJ experience to and from Hawaii that was changed by them 3 times from my original booking - and not to my liking.) I realize that all airlines with 737 Max are dealing with scheduling issues, however, I would just avoid the problem by choosing another flight outright. Food for thought...
Edit: For those who missed the announcement on Jan. 21, 2020, WestJet has pulled the 737 Max from its schedules up to June 24, 2020.
Also, here are the WJ Dreamliner routes: https://www.westjet.com/en-ca/about-us/fleet/787-dreamliner