This is a question that is frequently asked as cases where an employee resigns in response to their employer’s conduct are often called constructive dismissal. It is however still a claim for unfair dismissal and not a separate claim.
In these cases, you have the additional burden of proving dismissal if you are an employee. Claims for constructive unfair dismissal are statistically harder to win because you need to establish dismissal. The burden is on the employee to show that there was a dismissal in the legal sense. In such cases, the employee must show the following:
- His employer has committed a serious breach of the contract i.e. a repudiatory breach. The leading case is Western Excavating Ltd v Sharp 
- He has left because of the breach;
- He has not waived the breach known as affirming the contract i.e. he must not delay his resignation too long or do anything else which accepts acceptance of the breach;