I drove on the day of my discharge from hospital on day 3 - Her Loveliness was struggling to park the car!
Our Matron here (Lyn) will point out that you are probably not insured if you are incapacitated, and as you said, unable to perform an emergency stop. But as my prostatectomy was virtually pain-free, I was able to, and I probably started driving normally around day six or seven.
It seems I was very lucky with my recuperation compared to others here, and I felt right as rain on day 10, the day of the catheter removal.
If your husband feels well enough to drive, then go for it.
Best of luck with his recovery.
Cheers, John.