First of all, I am not sure whether this is the right place to post this, so please do correct me if there is a better place on the forum for this.

I am flying Singapore to Zurich on Sunday and would love to use my Qcredits to upgrade the flight to Business Class. As seems to be the norm lately, I wasn't able to secure the upgrade until now and have been told to try my luck again at the airport at check-in.
I'd love to know how you rate my chances of securing a business class seat on these flights. Currently expertflyer shows 14 empty + 4 blocked seats for the flight from Singapore to Doha and 11 empty + 4 blocked seats from Doha to Zurich. Has anyone of you tried to upgrade using Qmiles/Qcredits at the airport and not been successful?

Interestingly, I received an e-mail yesterday with the standard pay to upgrade offer (425EUR per flight). Is it safe to assume that they will usually open up all remaining seats for upgrades at the check-in.
Thanks!