What is the ruling on a divorced woman leaving her home for work during her waiting period ('iddah) if the nature of her job requires her presence at the workplace and she cannot obtain a leave of absence, and is it permissible for her to conceal the matter of her divorce from her colleagues at work?

The fundamental principle is that a woman in her 'iddah (waiting period) should reside in her husband's house where she was divorced, and she should not leave except for a necessity during the day, returning at night. If the questioner needs to continue her work and has not obtained leave, then there is no impediment to her continuing her permissible work.