You're the one whose being dishonest here, at least partly. From what I've read of self-defense laws in the UK, you can use "reasonable" force to defend yoursel

You're the one whose being dishonest here, at least partly. From what I've read of self-defense laws in the UK, you can use "reasonable" force to defend yourself against attack (try measuring that precisely in the heat of a moment where you don't know your attacker's aims) but yes, you can actually be prosecuted for using force against someone trying to steal from you. Even something as shitty as a google search will show that your claim is demonstratable untrue.