I have previously driven a petrol/diesel engined vehicle. Does it matter if I change?

There is hardly a lot of difference between driving a petrol or diesel engined car.

people worry unnecessarily about the difficulty in changing from one engine type to another. In reality there is a difference in driving any two vehicles so you will find the new car strange if you change instructor no matter what they drive.

Your new instructor will be expecting you to take a while to become fully accustomed to their controls so do not worry. A patient instructor will give you all of the tips that you need to become comfortable with their vehicle quite quickly.