Dave
As far as I can see, you want a course on how to safely clean carpets, get a good understanding of the various methods of doing so, the machines to use, the products to use and an understanding of the way to avoid the pitfalls.
Don't think such a comprehensive course exists. If it did, it would take abouit four days to deliver. But !
For the technical side and the actual qualification, you will get this by completing ( and passing ) the IICRC courses of which there are many.
For hands on, there are a number of those run by the NCCA, eg, they recently had a stain removing course.
I've attended many over the years, but a friend recently spent two days at Ashby's on reckoned it was an excellent practical course, with plenty hands on.
Most of what you need to know will come from experience and there are two things you must avoid,
Overwetting, which is very common with hwe machines, best practice, is to prespray with a product which will release the soil from the fibres, some need aggitating, followed by rinsing the soil laden prespray from the fibres. Simple really, but, if you move too slowly, or fail to release the trigger before you get to the end of the back stroke, or keep the trigger up on the forward stroke, too much water will go down.
Overstrength prespray.............follow the instructions, spray a mist on to the carpet, it's not the same as cleaning pathways. Some chemicals need aggitating to work effectively, others need a few minutes dwell time.
You can rinse with only water in the tank, but with so many chemicals added to our tap water a small ammount of acid rinse gives some security against colour runs.
There are a number of powerful portables which will do 99% of what you come across, t/m's have more power, but less flexibility.
As I said that is the basic information, but a couple of days at Ashby's or Alltec or Prochem would be beneficial.
Have fun
robert m