willo I found this for you taken fromhttp://www.learnerstuff.co.uk/learning-to-drive/private-practice.htm
Learning to Drive with Family or Friends / Teaching Someone To Drive
Learning to drive with family or friends can save you money and help you get to test standard quicker, but we recommend you always use a qualified Approved Driving Instructor and just practice with family or friends. You should also ask your A.D.I. when he or she thinks it is time that private practice with family or friends would be of benefit.
If you are teaching someone to drive you will need to have L-Plates clearly displayed, appropriate insurance for the learner driver and you must have held your licence for a minimum of 3 years and be at least 21 years old. It's also recommended that you have a rear view mirror fitted when you are supervising a learner.
Note: Remember Learner drivers are not allowed on Motorways!