From today new laws apply to those caught using a mobile phone while driving a car in the UK.
You will now be liable to a £60 fine and 3 points will be added to your driving license (this includes provisional licenses).
The laws apply:
While driving and the vehicle is in motion.
When you are stopped and stationary at a traffic lights.
If in a traffic queue or slow moving conditions on any road.
So as a learner if you are caught you will have 3 points added to your provisional license, in addition to the fine, your supervisor could also be penalised for abetting the offence.
Those supervising learners also need to be aware that while supervising these laws apply to them, and applies to texting as well as making/answering phone calls. If you are using a driving instructor and they don't obey these rules, you should change ADI ASAP and report them to the police, as not only are they not being professional, but they are being a bad example to those they are teaching.
More details at Road Safety Website.