Although we always recommend that, before starting the course, you already get down to work in order to buy in advance all the materials you need, it is also possible that, due to one reason or another, you have not been able to acquire some type of item. It can be a serious inconvenience. But, in any case, it has a solution.
Most of the basics, like the pencil case, pencils, pens, and notebooks, are easy to buy. You should not have major problems, unless they ask you for something specific. However, the textbooks they are another story, since they do not depend exclusively on the store. To give you an idea, each establishment receives a certain number of copies but, in the event that they do not have them, they will be forced to request them from the publishing company.
During the first weeks of the new course it should not be difficult to buy the textbooks. However, if a long time passes, you could have problems, since some publishers stop distributing them. In that case, you will have to resort to other sources like the second hand, the Internet, or even the study center itself.
In any case, we recommend that you get all the materials to the as soon as possible. In this way, you will not only have them, but you will also avoid problems that could affect your studies. Better to get rid of them than not have to put a "patch" on in a hurry.