Snapper, one has to quit rather than be fired - and quit fairly promptly - to be eligible for constructive dismissal.
Constructive dismissal is when you’re forced to leave your job against your will because of your employer’s conduct.
You should try and sort any issues out by speaking to your employer to solve the dispute.
If you do have a case for constructive dismissal, you should leave your job immediately - your employer may argue that, by staying, you accepted the conduct or treatment.
HMG guidance on constructive dismissal
crossed with ANA