You don’t have to go through insurance, many people don’t.
You don’t have to go through your insurance but come renewal time if you answer no to “any accidents in the last five years” you are committing fraud.
Would you, Jamba, be able to carry on your job if convicted of fraud?
It’s unlikely one would ever get found out, but is it a risk worth taking for a couple of hundred quid? The OP’s missus’s premiums would go up a bit for a while but the other lady would take the real hit. That’s her problem. She might learn to look where she’s going. Could be a baby Robin next time.