I am on a craft mission to work with some clay

I have no idea about pottery. I am on a mission to make something. I want to make a tiny little dish. Think about the size of a plastic bottle cap. It will be for my hamster.

I would like to use one of those packets if clay you can find in craft shops. I would also like to use a varnish that will seal the clay and allow me to use it for food or medicine or drinks and wash it.

Can you help advise me please.

Will a packet of clay from a craft shop work? What varnish do I need?