I've only flown WT+ twice YYZ-LHR. Once it was half empty, allowing me to switch from my aisle seat (chosen online) to a much roomier bulkhead aisle with nobody beside me.
Second time it was full, but I had my pre-selected aisle.
After trying WT+, I decided I'd only use it in the future strictly for the deal to upgrade to there to Club for 25,000 points. That does make it worth the extra money. I realise you are not able to do that (yet?) but if you have a lot of YYZ-LHR trips to do, it would be smart to spend time on this board sluething all the ways to crank up a hefty BAEC mileage balance and do the upgrade.
I was underwhelmed by WT+ itself. The extra space is not that big, especially if you get squirrelly stuck in a plane for 10 hours. Apart from the extra space, it's just a curtain.