Both are correct. The second one implies that there is a possibilty that the doctor will be able to check the X-rays, while the first does not.

As Matt has said, they are both correct. Believe me - your grammar is fine. There is a difference in meaning, however. "The doctor WON'T have had a chance to look at your X-ray yet' suggests that the speaker is sure that the doctor hasn't seen it yet. "The doctor MAY NOT have had a chance to look at your X-ray yet." suggests that thinks that it's possible that the doctor hasn't seen it yet.

First sentence is incorrect. As far as I know the Future Perfect is used only when there is a sequence of tenses. But your example doesn't contain it. Maybe the others sentences in the text contain it but I'm not able to know it.

Well first of all, you spelled which wrong. WHICH IS CORRECT THE DOCTOR WON'T HAVE A CHANCE TO LOOK AT YOUR X-RAY. Don't put "have had." That is the correct way. Indicating that the doctor will not look at the x-ray at all or never. THE DOCTOR MAY NOT HAVE A CHANCE TO LOOK AT YOUR X-RAY YET. Again don't put "have had" This is the correct way. Meaning the doctor will look at your x-ray, but not now. The most correct one is: The doctor may not have the chance to look at your x-ray yet.

Right, both are correct but the sentences have different meanings.