caa website has a list of repat flights with flight numbers. The example you give with QR, these are using BAW callsigns.
As most if not all of the ZB fleet are leased are the aircraft still on the ground where they landed in the U.K. Or have they been flown out by the leasing companies already?
Glad to see EI offering type rated flight deck crew a recruitment event, hopefully similar will follow for cabin crew