You and your Therapist will draw up an agreement at the first session, which states what is important to both of you to ensure a safe and productive working environment. You may have some personal requests, for example, that a door is left slightly ajar, that allowances be made for medication, etc. The Therapist will usually include the need for mutual trust, confidentiality and punctuality.
Therapists will often waive their fee if notice is given outwith 24hr - 48hrs that you will be unable to make your appointment. However, as the Therapist will often be travelling themselves, it is reasonable to expect that a failed appointment without notice will result in a cancellation charge.
It is best to agree all of this at the outset to avoid misunderstanding.