If you have resigned, either formally or informally, because you can no longer stand the bullying or harassment, you can make a claim for unfair 'constructive' dismissal. Your claim is made under employment protection legislation, and must be submitted to an Employment Tribunal within three months of the day you last worked.
However constructive dismissal cases can be hard to win, so this should be a last resort. Of course some situations are so bad that walking out is the only possible course of action, but if at all possible you should take expert advice before doing so, and make sure you exhaust any internal procedures. There is more about constructive dismissal in the rights section of workSMART.
Just One More Click: Doggy drama about staying safe online at work.