I don't think it's such a bad thing to want to wish someone important happy new year, but it's something I wouldn't do as a client rather than a friend or family member. I feel close to my therapist but I would not text her during her break. As much as she means to me, I am her work and I think if she wants a complete break fom it, then she deserves it. If it's something you want to stop yourself from doing, I'd suggest writing down what you wish you could say and giving that to your therapist later.