Whether you are still a PDI, approved, or working for a driving school, you will need a completely different kind of car insurance. There are many types of cover that you could need, depending on what sort of instructor you aim to be, these can include:
Mandatory by Law
Any driver (including learners) cover - allows you to teach any licensed driver
Cover for Hire and Reward - because you will be collecting money from your client you legally are required to have this cover
Additional
Replacement Dual Control Vehicle Cover - as you will be taking learners there could be a danger of damage to the vehicle. Therefore, you must have this so you can carry on working even while your car is being repaired.
Negligent Tuition Cover - protects you against any claims your learners may make.
Diving Off-Road Driver 14+ - this cover will allow you to teach those who are 14+ off-road.
Comprehensive Driving Other Cars - if you have to carry out a demonstration drive in your client's car you will need this cover.
Modified Vehicle Cover - As an instructor, you may have to carry out modifications to your vehicle in order to teach, such as dual controls and an additional speedometer.