If you resign because your employer's behaviour towards you amounts to a fundamental breach of contract then you could claim constructive dismissal, subject to eligibility.
The treatment you have received must, however, be so serious that you can say it goes to the root of your employment contract. An example could be a failure by your employer to deal with your serious complaints that you are being bullied by your manager.
If you ultimately feel you have no alternative but to resign because of your employers' conduct towards you, then your resignation may constitute a constructive dismissal. In such circumstances you can apply to an employment tribunal claiming unfair dismissal. Strict time limits apply: you must normally bring a claim against your employer on Form ET1 within 3 months of the date that your employment terminated.
