Hello!
This decision is really up to you, but there are a few points that I would recommend considering. Firstly, is the forensic path accredited by the BPS? If it isn't, are you considering any future careers that might require accreditation? Secondly (and most importantly!) are you interested in fully committing to studying this area for a year, or would you prefer that learning about it remains a hobby? You can always stick with the general stream and then go into a more specialised masters later on.
A psychology degree in general is a very useful asset for the future as you get so many transferable skills so I don't think you should worry about limiting your future career options, as long as you are able to discuss how these skills can be applied!
I guess the TLDR of this is that it's important to do something that you are passionate about, whilst also remaining realistic about the hard facts (accreditation, skills, etc). I hope you come to the conclusion that makes you the happiest!
-Kat (3rd year psychology undergraduate at Lancaster University)