It is nothing to do with the IA, it has never been allowed for cabin crew to upgrade for non-commercial reasons. If you were going to put your job on the line, it is unlikely you would risk it for people you did not know. I am sure there will also be lots of BA staff in World Traveller too.
We would love to have the power to upgrade your crew but it is very unlikely and would more likely be done by the ground staff at check-in if there was a commercial reason for doing so. To be honest it is unlikely there would even be space in Club anyway!
Do tell the crew that you are all crew too because I am sure they will make you very welcome, even if you do end up travelling in World Traveler