I have no experience with that product but suggest you still install cement board substrate if you decide to go that route. I would want to see a few installs and have a good warranty in case of failure.

Hmm. I was going apply the plaster myself. I have no experience but have been watching and reading tutorials. We had the cement boards professionally installed in the shower. The plaster seemed like something I could do myself. But I'm weary now that of I don't do it properly the shower won't be waterproof.

Not even sure where to purchase it ... Not easy to find

Hire a plasterer. They will do this in an hour and it will be perfect. You will do it in 4 hours and it will look ????

You should definitely hire professionals for the tadelakt work. An experienced plasterer makes something like 4 sqm/day. Google the company that owns the picture and you will find everything you need. You can PM me if you have any questions about tadelakt.

I have been using tierrifino stone - tadelakt for around five years now. There are some examples, descriptions and application guide on my website. http ://www.tadelaktsydney.com.au