To the scrapyard!
You need the whole front compartment wiring loom, airbag control unit, airbag (obviously) and steering column.
We had to do this for a customer at Nissan once who had a P reg without airbag.
Only real issue I can see you having is if your car is too early to have NATS in the key. If it does, you're ok, if not er...
Tell insurance it was fitted when you bought the car, you assumed it was fitted as standard. Gits!
Or you could look at it the other way, if you smashed yourself up in that way, chances are you will be injured differently if you ever have a biggie again.
I've never broken the same bones twice any time I've had a big accident and I've had quite a few, LOL!