I don't believe so. However, one thing you could do, especially out of YYZ, is book the last flight of the day on AP points with a J reward, but confirmed in Y. And show up at the airport for the earliest LHR evening flight (ie: AC858) and get yourself onto the J waitlist.

Unless J is literally sold out, you will travel in J, in priority over the non-confirmed coupon upgraders, even ones with "status".

Meanwhile, if for some reason, you can't get onto the first evening flight (ie: AC858), then your time can be spent in the MLL for 2 more kicks at the can.

Same deal at LHR on the way back. Fees/surcharges, unfortunately, are a small fortune on this route and exceed that of buying a revenue ticket at times -- not the best use of AP points IMHO, but you gotta do what you gotta do.