You basically need to ask yourself two simple questions: A) Do you want to become a doctor and have what it takes? B) Can you really see yourself working in mental health (a pretty grim area tbh - if you haven't any actual real life experience of it I highly doubt you'd be thinking the same years down the line)?
If doctoring isn't for you, forget psychiatry. If it is, every young doctor changes their mind about their specialty a thousand times so going into medicine already knowing what type of doctor you want to be at the end of it, is short-sighted.
Otherwise, your options are psychotherapy without DClinPsy or a psychologist with it. Note, doing a 3 year psychology degree leaves you with pretty poor job prospects once you graduate. To progress to become a psychologist, you'll need at least one year of clinical experience in a mental health environment and then a further 3 years of DClinPsy. That's minimum 7 years before you start actually earning, longer than it takes to do medicine and be a doctor. Ergo, it needs a lot of dedication and you need to make sure you really want to last the course.
Note, there's a wide spectrum of people working in mental health, from counsellors, to psychologists, to psychiatrists. These roles couldn't be more different: becoming a counsellor is a world away from becoming a psychiatrist for example.