Update 4 January:
Happy new year everyone!
Unfortunately, there's no news yet about our antenna connection.
Thanks for all the mails I got, expressing support and/or with tips on how to feed an antenna signal through a window that cannot be opened. Unfortunately, those tips are not usable: our only window is to the corridor, not to the outside. That is because our club room is in a part of the building that originally was only meant for storage, so no outside windows were installed.
Those of us who have had any experience with university amateur radio clubs, and the strange workings of the schools that support them, will be less amazed that a club dependent on outdoor antennas would be given a room with no access to same. Universities are like this.