if I have a Hermes apple watch do I get access to all faces or just the Hermes faces?

You will have access to all the faces.

I have a Hermes Apple Watch.

Yes, you will have access to all standard faces and unique Hermes faces that no one else has! You also will get a unique orange Hermes sport band in the box. As far an I know, the only faces you will not get are the Nike faces from the Nike watch.