No point at all, because there is no grey area in the law. Not saying I agree or disagree, but that's the law, so I'd recommend you just take the hit and get on with your life.

This website explains it pretty well:
http://www.nopenaltypoints.co.uk/leg...e-running.html

It is indeed an offence to use a mobile phone whilst a vehicle is stationary in a lay-by or at the side of the road with the engine running, and the important point to note here is 'with the engine running'.
Many people think that 'driving' refers to actually moving along the road in your car - and in most instances, this is the case. However, if you are sat in the driver's seat of a vehicle with the engine running, then you are technically in charge of that vehicle, so the penalties that apply to using a hand held mobile device while 'driving', do apply to you.
This means that even if you are sat in a lay-by, away from the main flow of traffic and you use a hand held mobile, then you open yourself up to prosecution.



The regulations regarding mobile phone use are clear:
As a driver, you must not use a hand held mobile communication device to either text, call, or carry out any other activity that requires connectivity, such as web surfing. If you break these rules and are found to have been doing so, then you are at risk of being given an automatic fine - and this includes using a mobile device while driving - even if you are sat still in a traffic jam or at lights - it is still classed as a specific offence, which will lead to automatic fine and points on your licence.
Currently, the law states that the fixed penalty for using a mobile phone while driving is £60 which rises up to £1000 should the case end up in court. The current points endorsement is 3, although it can be raised if the police feel that you were driving dangerously due to using the device.
Even if the you are speaking on a 'hands free' mobile device, if a police officer deems that your driving is falling below the expected standard, then you may find yourself charged with careless or dangerous driving, which can lead to a fine, between 3-11 points depending on the severity of the offence, the circumstances surrounding it and the decision of a judge, and worst case scenario - disqualification and even a spell in prison.
So the moral of the story is clear - if you pull over, switch your engine OFF before you make or take that call. Then you'll be in the clear.