Would it be best to see a psychologist or a gp for mental health assistance.

It depends...: It's hard to know without more details but a GP will most likely treat with pharmaceuticals while a psychologist will treat with counseling/psychotherapy. I believe it's usually best to start with a psychologist as they'll help you work through your issues rather than prescribe a drug for symptoms. After seeing a psychologist he or she will tell you if you should also see a GP or psychiatrist.

Either: A GP should be able to determine if you have depression & rule out medical causes for symptoms. On the other hand, I always recommend psychotherapy which you can get from a psychologist. The psychologist can do an in depth assessment. The psychologist would likely refer you if it looked like you needed psychotropic medications.