Without question, you should report his behaviour to the director of inspections at OFSTED. Exacting standards have been set for the conduct of inspections and most teams have been scrupulous in upholding them. Where there have been proven instances of unsatisfactory conduct, inspectors have been dismissed.
If you are worried that your report might be adversely affected by a complaint (which I do not believe would happen), you might choose to wait until the process has been completed before writing to OFSTED. But do it.
A geography teacher at this school has refused to cover for an absent member of the P department, saying that he is not qualified to do such work. Is he right?
Yes and no. He is right that he is not qualified to conduct a PE lesson, which involves activities which he has not been trained to supervise and he ought not to be asked to teach such a lesson. Were a pupil to suffer an accident in such a situation, the school might be held to be negligent because adequate supervision had not been provided.
On the other hand, if he is being asked to supervise a group doing a cross-country run or kicking a football about, any able-bodied teacher might reasonably be expected to cope. As a last resort, he could simply supervise the class for private study.
He cannot, therefore, refuse to cover for the absent PE teacher, but he cannot be directed to conduct an activity for which he feels unqualified. If he is, he may use the grievance procedure, on the grounds that such a direction is unreasonable.