Think of self defense as a life long pursuit of collecting the necessary tools to keep yourself and loved ones safe and Aikido as one tool in a collection of tools to be used for self defense.
If you need protection immediately, I would get a gun and learn how and when to use it. Then let everyone know you got a gun and you know how to use it.
Isn't this young man 16 years old ? He would have to obtain or carry it illegal I don't know British laws .I guess a lot of factors would come into play .I don't totally disagree but maturity plays a great deal in responsibility of carrying a gun.I wish nothing but good luck to this young man.But a gun maybe opening him up for more problems.