If you want to be a psychiatrist I would suggest that once you are into medical school you do an intercalated year Batchelors degree in psycology. This is an optional year three. Then complete your clinical three years, then do your foundation two years. Then to CT in psychiatry, then do ST in psychiatry (4 years) with or without a research degree MD or PhD ( 2-3 years) in a specialised area of psychiatry, and then do a fellowship ( 1 year) either in the UK or overseas in a specialised area of psychiatry ; total training aged 18-33 years approx. Some specialities take a bit longer. With that training you would be competetive for the best NHS jobs plus some private practice in combination; leading to a very satisfying career. Investing time at the beginning in biology at some level is of value; however the most useful school subject in “real terms” is the Statistics you study with maths. I would always respect an A level in Pure Mathematics with Statistics ( if your school offers that option), although it will all be covered at medical school anyway.