Is it possible to notify users of a timetable modification by e-mail?

Yes. In the module Daily management and absences, go to the timetable of the concerned resource. Select the course on the grid, then click on the button at the bottom left of the course form. In the pop-up menu, select the option Send by e-mail; in the menu Sending of an e-mail, select the appropriate e-mail template from the list on the left.