In addition to whatever insurance you can find, consider joining the Armed Citizens Legal Defense Network.
The Network was started by Marty Hayes (full disclosure: good friend of mine), and includes a lot of well-known people: John Farnam, Massad Ayoob, Tom Givens, Jim Cirillo, Jr.
The basic deal is, joining the Network as a member gives you (and your lawyer) access to free and immediate expert advice following a defensive gun use, discounts on training fees and other goodies, access to a vetted attorney referral list consisting of lawyers who are knowledgeable about defensive gun use, and (possibly) help with your legal bills. Financial aid isn't an automatic thing; your case would first be reviewed by a panel of experts to determine if they reasonably believe your actions were not criminal. The panel currently includes Massad Ayoob, John Farnam, Tom Givens, Jim Cirillo, Jr., and ex officio members Marty Hayes and Vincent Shuck.
The Network is not a pre-paid legal plan, and it's not insurance. It is a membership organization allied with a non-profit foundation (20% of member dues go to fund the foundation's war chest). The organization is dedicated to helping certified good guys prepare for foreseeable legal challenges beforehand, and the foundation will be available to help manage the legal situation afterward.
I joined as soon as I heard they were open for business.
Oh, and as you are shopping for insurance, remember that most types of insurance only insures against unforeseen, unintentional
acts. But for this, you need insurance against an intentional
act, the purposeful act of killing another human being. For example, your homeowners' insurance will not cover you if you purposefully set fire to your own home, but if a fire accidentally starts in the wiring or while you're cooking dinner, it will cover that. Similarly, you'll find that when you query the insurance company as to whether your homeowners' insurance will cover a shooting in your home, it's quite likely the agent will believe you are asking about an accidental or negligent shooting, not about a deliberate shooting in self-defense. Even for those rare types that will cover a deliberate self-defense shooting on the civil side (eg, you got sued), I don't believe you'll find that the insurance will cover the cost of defending yourself against a criminal
charge. And yet a lot of your legal costs after a self-defense shooting will be incurred while dealing with the potential or reality of criminal charges.
The NRA does offer this type of insurance to members, but be sure to read the limits carefully.
Hope that helps.