interesting comments i should add is no actually me but a friend personally i think if a company has made a significant investment in you then repaying it if you leave is fair enough as if they are unable to get there investment in either work or default payment payment they may deside that training people is not economical and not offer it
Why would anyone accept a contract signed VC? Accepting a contract that was invalidated this way would be pointless.
Especially as these contracts would offered before you commence the training, no valid signature, no training and possibly no job.
But don’t let that stop you standing up for yourself. 