I'm in the same situation. I'm not a plasterer and new to the forum, lurking around to get tips for breathable or lime plastering. Hey, how hard can it be...?
...or 19th or early 20th century buildings.
I drilled into the walls of a Victorian terrace (built 1902) to inject a damp course and the brick and mortar dust from the outer courses came out as mud. I think it's partly because of the c.1980s render.