Our professor is returning to England tomorrow, you know.
Literal
Tomorrow, our [possessive-の] professor [topic-は] England [to-に] return [feminine-のよ].
のよ is a sentence-final combination: の (explanatory/softening) + よ (assertion), distinctly feminine. Used to assert or share information in a soft, feminine-marked way. Compare with the masculine のだよ/んだよ. 帰る with an に destination — the place the person returns to.