Forensic psychology is not forensic psychiatry; the latter is a subspecialisation of the medical specialty psychiatry, and requires a medical degree. The former is a subdiscipline of psychology, for which you would need a psychology degree. You can become a "forensic scientist" with a range of science degrees, potentially including but not limited to chemistry, biomedical sciences, biology, etc. You don't need to do a specific degree in forensic science (and there may be benefits in not doing so, since as above the field is heavily oversaturated and not really a growth sector, so having a more general science degree enables you to apply to those roles but also to other positions outside the field if you aren't immediately able to go into that area).
In general I would recommend focusing on doing a more "general" undergrad course (e.g. depending on which route you want to go, psychology or a science course in chemistry or the biological sciences broadly), and then do a specialised masters in the "forensic" side of the field if that is what you want to pursue. This keeps open the possibility of the forensic sector (either with or without the masters), as well as giving you a range of other options in case your interests shift, or if you aren't able to immediately find a job in that sector when you graduate.