There are a number of providers of driving school supplies.
Supplies that you may want are stationery such as business cards, appointment cards and driving lesson plan diagrams. Driving School Supplies have been one of those businesses but they seem to be having troubles at the moment. Other providers include RCM marketing, Ideas4ADIs and ADI Ninja.
There is considerable overlap in the different supplies offered by different businesses. Some have a massive stock of every kind of obsure item you might need. Others supply just the basic essentials or theor own niche products.