Agree with the above. Even if you don't think you're deserving of this opportunity and that nothing will come with it, you're still in with a much better chance than the many hundreds of students who didn't even get an interview offer. There is little to gain from tanking it because you think you won't get in. All tanking it will do is make sure that that is a certainty; whereas, if you give it a try, sure you might still be rejected at the end of the day but you'll know that you gave it your best chance and you'll also have developed some interview skills to boot.
If you are genuinely keen on doing medicine, there is also graduate entry to consider, which at the end of the day will also necessitate an interview. Having had an opportunity to hone your interview skills before you even begin that pathway is an excellent way to develop your skills when, inevitably, you have to sit an interview for graduate med.