Plato is definitely someone to read. Indeed, he helped lead Augustine to Christianity and his natural theology, as well as his ethics, were essential to Christianity (read Catholicism) developing it’s own rational theology.
It is no accident that classical philosophy came about when it did. Providence is a special thing, and the compatibilities of Christian theology with Platonic philosophy are quite striking. I would recommend reading Augustine, as he locates the weaknesses of Platonic philosophy quite astutely as regards Christian theology (start with the Confessions, not too difficult).
Of course, Thomas adopts much of Platonic philosophy as well.
By all means read Plato. In fact, as a Catholic I recommend reading him.