Bear in mind that many TC guys may now be sitting on multiple job offers. Tui have moved fairly quickly, but the terms are the weakest. Jet2 seem to have started getting offers out this week. For an FO there is almost £20k difference between the 2 companies..
Having committed to expansion, they may not get everyone they want/need to join at this point.
I don't know what contingency they have, clearly non TC people, currently in a job are unlikely to be able to join TUI inside of 3 months, nor would be willing to accept chopped down part year part time stuff.