Restrictive covenants will only be valid if they protect a legitimate business aim and the protection is no more than is reasonable to protect the interests of both parties and the public.
The reasonableness of each restriction must be considered in light of who the employee is. As such if exceptionally burdensome restrictions are placed on a junior employee they are less likely to be enforceable.
They will not be enforceable if the employer has made a fundamental breach of contract that the employee has not affirmed.
If a clause is found to be enforceable and an employee is in breach an employee may result in, the employee having to pay damages, account for their profits or be subject to an injunction preventing them from carrying out the action which caused the breach. The best way to avoid being subject to such proceedings is to refrain from carrying out the actions in the clauses or to get written agreement of release from the covenants.