Looked at doing courses a few years ago, they are all done by people who just want to sell there products and machines...and have not done much hard floor cleaning themselves...so im self taught, through years of research and practising on floors i laid in my lock up...there are no stone floors that scare me anymore, i can grind them, diamond polish, hone them etc...also i repair cracks and chips with resin. And i lay them too.