Cheers Graeme. I've got an air powered 3/8 driver.
One more question. Is it best to have the car as it stands, air suspension raised or the front wheels on ramps?
Thanks.

I had mine on front ramps at normal height but was cramped for room underneath trying to get both hands up to hold inappropriate tools, but really wouldn't have wanted it any higher from the top. Your air-ratchet is bound to be smaller than my battery-operated one but being able to use just 1 hand will make the biggest difference.