6 weeks is a general guideline offered by some members of the medical profession. Other practitioners suggest 4 weeks. None of these suggestions are legally binding and should be presented as "likely" timescales before you feel able to drive safely and comfortably.
Information guidance published by the National Institute for Health and Clinical Excellence (NICE) states...
"After a caesarean section, you will not be
able to do some activities straight away such as driving... You should only start these once you feel that you are able to do so and when they do not cause you pain. If you are unsure, you could discuss this with your midwife."
http://guidance.nice.org.uk/CG13/publicinfo/pd f/English
In any eventuality it will be the decision of your insurer which dictates whether or not you can drive under the conditions of your policy.