From our experience, around 90% of what is assessed in medical school interviews can be prepared for.
Topics assessed include a personal assessment, which includes critique of your motivation for medicine and your work experience etc. Some of the harder stations assess your communication skills, especially when in conflict and your ability to show empathy. Medical schools are increasingly using professional actors and media in their assessments. It is possible that your sixth form offers such training - but are they aware of all the current trends? It is possible to see the improvement in scores following medical school interview training, as well as an improvement in confidence, especially in students that can be normally quite reticent. It is not a simple matter of regurgitating coached answers. You will need to learn frameworks that can be used for multiple scenarios that can be put to you, for example in the area of ethics. Even though you may not get the correct answer, you will show the examiner that you have the ability to think through complex scenarios.
Having a doctor in the family, especially one that has experience in medical education is an obvious advantage. You can learn some of these skills from a book, but then you will need to learn how to apply them face to face in an MMI station. Fellow students working together might be useful, but remember they are also your competitors!.
Blue Peanut Medical