The NHS has been adequate imo, the wait times can be pretty gay but the services offered are fairly good, at least in my area which doesn't have a huge population. I imagine overpopulated shitholes like London will probably be different. I think the main problem in the U.S is due to them not having a lot of mental health facilities and or programs that are accessible to the general public. From what i have gathered, you basically get given medication and sent on your way with zero to little aftercare.
Also, if you look at the areas that comprise the majority of violent deaths by firearms in the U.S, it's "urban" areas in questionable cities and the firearms are nearly always illegally owned. Honestly, if you removed nigger crime from the statistics, the overall rate of violent crime especially in regards to firearms would drop like a lead balloon.