The tapes are dire. Get Cap 413. R/T is by far the easiest bit of flying. Do as much of the R/T during your training flights as you can, right from the start. If the flying/nav workload is heavy, your instructor can step in and do the radio for you and a good instructor will know when to do so and when to leave it to you. If your instructor wants to do all the R/T, get another instructor. Have fun.