In my opinion, there is a scope for arguing that supply of uniform, shoes & bags to students to whom education service is provided, is naturally bundled and hence is a composite supply for the following reasons:
1. Generally, the students are mandated to purchase text books, note books, uniform, shoes, stationary etc... along with education services from the school itself.
2. A non-student is not allowed to buy books, uniforms, and stationary from the school. These are generally to be provided to the students of the particular school only.
3. From the student/service recipients' perspective, it is seen a single bundle.
4. Many private schools are doing this practice.
5. All the above goods are integral to one overall supply i.e. education service.
That being said, this position may lead to litigation also, and one has to take a call based on all facts and circumstances.