もし臨時急用があれば、前もってあなた言いますが、よろしいでしょうか？
如果临时有事的话 我提前和您说 您看可以吗

If last-minute arrangements come up, I will inform you in advance. Would that be alright for you?

If anything suddenly comes up, I will inform you in advance. Would that be alright for you?