Showers how-to

I've been reading Ianto and Linda like gangbusters and am ready to start experimenting. Before I get too far, what is the best wall treatment for showers and bathrooms.
The pics of concrete stucco collapses in Devon make the point loud and clear that cob needs a breathable skin.

But what about the shower?

In a work Tadelakt, tile, stone or some other water proof or highly water resistant material, even wood if done correctly.

Clawfoot tub with 360 degree curtain or put in the middle of the room with waterproof walls separate from the cob.

It can be done if you think about your layout. You can hide the stool behind the shower for privacy.

I'm wondering something similar. I have read with great interest "Building With Lime: A Practical Introduction", but not much is said about the bathroom/tiles, that sort of thing. Specifically-- if tiling onto lime/clay plaster, what gets used for grout? And some sort of hydraulic lime would be used? And is it suitable to be the wall of a shower?

We're remodelling our home, which is adobe bricks, and replacing the current cement-lime plaster with clay-lime plaster.

My problem I run into is that my wife already bought last year the shower cubicle (glass doors, fiberglass bottom thing) she liked, but it will still need tile walls on two sides. I think the tiles are already purchased as well.

Are common, glazed ceramic tiles over an earth wall even OK? How will it affect wall breathing there?