If you require a client to give you notice when ending your relationship, a change to your Policies and Procedures I suggest is around this sort of language: “…it is your obligation to notify me at least one month in advance…”
Leave that out. It just makes a reader want to say, “Or what?” I mean, seriously, what would you do if the client doesn’t give that notice? “Force” her to pay you? How?
It’s language with no real body under it because, as a practical matter, you have no authority over her, and over a month's worth of work, you’re unlikely to sue her for it to “force” her.
Wherever possible, don't be a hard-ass. Hard-assery that you won't enforce is just stupid, and the truth of the matter is that if someone wants to leave your practice, you want her gone as quickly as she can go so you can both not have to work with someone who doesn't want to be there, and find a new client that you'll love and feel great about having in your practice!