no land really needed, just find a woods and creek that the owner doesn't care if you pick some weeds or even find a local garden that they will let you have some weeds....and after reading the school of natural healing book, you should be ready to get started making your own herbs.
you will learn how to make syrups and tinctures. powders really should just be bought as an already made formula, or at the very least a different powders that you can mix together yourself. trying to grind your own powders is a waste of your time (in most cases) You will not learn how to make the sprays.
you got to be careful with how you grind powders down. Too fast, too much heat etc can destroy a lot of what you are trying to get out of the herb. you also have to ask your self how much your time is worth.