The statin class of drugs are very important part of the treatment for many patients with high cholesterol. You are correct in that statins do have the potential to cause liver problems. The best type of physician to consult with about this problem is a primary care physician
such as a family doctor
or internal medicine doctor
or a specialist such as a cardiologist.
While statins do have the potential to cause some minor liver damage, it is usually not severe enough to cause any long term problems. For this reason we will often use statins even in people with a history of alcohol abuse or liver damage. In these patients, we just monitor their liver function a lot more closely than we would otherwise. The history of alcohol abuse is important for his doctor because he will at least need a baseline set of liver tests to make sure that the statin does not cause any additional problems. In most cases, the benefit the drug gives outweighs the risks.
I suggest that your father go back to the physician that prescribed the statin and ask if his history of alcohol abuse played a role in the decision about the statin. It is possible that his doctor will want to get liver function tests which can be done with a blood draw (if it hasn't been done already). If they are at all abnormal, his doctor may decide to stop the drug, or just monitor the tests to make sure that his liver function doesn't get worse.