Medicine is very competitive and it will depend on the medical school. The vast majority will need 3A Levels at grade A or above. Some such as Oxford Cambridge or Imperial will need A*AA or higher check with the entry requirements of the university the vast majority will not consider retakes in A2 to achieve the higher grade. There is also an aptitude test call UKCAT or BMAT (for Oxford Cambridge Imperial and a few others) genenerally you will need to score around 670 in the UKCAT test to stand any chance of getting an interview. Don’t know what is for BMAT. A good personal statement is crucial some form of voluntary work in a hospital environment also helps (check with your local hospital).
I have known A level students with 4 A* grade who did not get a university interview. So you will need a backup option and most choose the biomedical sciences on many courses if you do well in biomedical there is the possibility to transfer to med school
Just a minute I thought this was about engineering and not how to get into med school. If this is what you want to do good luck and be determined