My insurance company didn't require me to get any formal 'sign off' (would form would that take, exactly?) after CS to start driving. I rang them when I was pregnant and checked.
They said that people have operations all the time, and it is up to them to be responsible and only drive when they are able. Of course, someone might want to see a doctor to involve them in that decision, but people have operations ALL the time, for hernias, appendices, leg surgery.... eye surgery, for goodness sake! the principle for CS is no different. I sometimes wonder if an insurance company telling someone to 'ask their GP' is a commonsense suggestion, not an insurance requirement. A verbal OK from a GP, relayed by a patient to an insurance company would seem a little flimsy in court, unless that GP had recorded it in the appointment notes.
The issues for driving after a CS are (a) physical strength. Lifting your legs to work pedals and having enough strength and control to do an emergency stop is obviously vital. If you have lingering abdominal soreness, this might be a problem. Some women might find the torsion involved in steering tricky, I don't know.
(b) you take longer to heal internally than you do externally. If you are in an accident, you are more likely to bleed internally or rupture something if you are still healing. This boils down to our attitude towards risk. Some women might feel their risk of crashing is very low, and if they feel fine and strong after 2 weeks (as I did after my ELCS), then it's a risk worth taking. We risk an accident everytime we get in a car, after all. Other women won't want to take any risks at all, and will wait longer than 6 weeks before driving.
I guess if in doubt, have a detailed conversation with your insurance company. I have friends who had been told by NCT teacher they couldn't drive for 6 weeks after a CS, and for a couple of them (rural like you) this was a HUGE PITA, as they felt they could drive beforehand but didn't.