I can understand the drive to wanting a gun, if it were possible it would be my option as it's ready to go at a moments notice, unlikely to fail if you do it right and it's quick and painless, in theory.
However we UK people are just screwed in that aspect, ironic really as I've allways pittied America for having easy to get guns, and now I'm jealous.
The best way I could get is a tank of nitrogen and a gas mask, in theory, when the time comes I need to use it I'll be unconscious within 30 seconds and then just gotta pray nothing goes wrong.