You should always take professional advice before claiming constructive dismissal.
Constructive dismissal is where your employer has fundamentally breached your contract of employment and you have resigned as a consequence. Examples of a fundamental breach can include:-
- a cut in salary or other benefits without agreement
- making it untenable for you to work by reason of your employer's unreasonable attitude
- imposing a disciplinary or performance process that is grossly unfair and disproportionate
- suspending you without good reason