I never felt the need for one with either of my kids to be honest, babies sleep most the time in the car! Anything that can become loose is considered a hazard too!
If in the U.K., you need to inform your insurance company if you plan on switching the air bags off (all if you're driving for the first 6 weeks after section) and obviously if you've switched them off, have an accident and haven't informed them, your insurance is worthless!! Xx
where did you find this info hun? since my airbag button only turns passenger one off specfically for infant seats.. and can easily be switched back on as and when needed? x