Relationship between modules and lecturers is many-to-many, hence the 'junction' table lecmods.
Main form bound to modules for viewing module details. Move to new record row to create a new module record.
Subform bound to lecmods. The module code will automatically save in the subform - this is what the Master/Child Links properties accomplish. Select an existing lecturer from combobox. If you want to create new lecturer record 'on the fly' during data entry of lecmods subform, this will require opening the lecturers form, enter the new record, requery the combobox so the new record will be available. This can be accomplished manually with intrinsic tools - open lecturers form from Navigation Pane, enter new record, close form, click Refresh All on the ribbon. Select new lecturer from combobox. Automating these steps will require code (I use only VBA). The more 'user friendly' the more code.