Is it the injector sleaves that are leaking? If so then yes this will be the lilkely cause of your problems.
Unless one of the garages has confirmed the head gasket to be faulty I wouldn't get it changed, it's a lot of work and the head on that enigne can't be skimmed, if it warps during removal or installation then you need a new head, not worth the risk if it isn't confirmed to be faulty. Unless the garage needs to remove it to change the injectors but I doubt it.
Sorry I don't know enough about that engine to give a definitive answer.