As a graduate, my advice to you is that if you have good grades, you should consider taking another gap year before pursuing your studies in different course. Get a job! Don’t feel like you have to pick another course because everyone is at university and you feel underachieved or your parents. It is important to remember that it only takes one offer to become a dentist, so it may be worth taking the extra time to secure the right opportunity for you. You don't want to find yourself committed to a three-year course at university only to realise that it is not the right fit for you in the future and regret it.
If you do decide to pursue a degree in Biomedical Science, it is important to check that it is accredited by the IBMS. This will ensure that you are eligible to practice as a biomedical scientist in a hospital setting after graduation. I would say look into pharmacy which is a better option compared to biomedical sciences. It’s much desirable in terms of future prospects.
In the event that you have good grades but did not perform well on the BMAT/UKAT, consider retaking the exam and practicing your interview skills. This can increase your chances of success in your application to dental school. Don’t give up! GOOD LUCK!!