Lessons take place on a weekly basis during the school term (I go by the state school dates for all of my pupils). I am happy to arrange optional additional lessons during the holidays.
Payment is made on a half-termly basis, in advance. I charge for all lessons whether attended or not. In the case of lessons missed due to illness (and for no other reason) I will to try reschedule the lesson before the next half of term begins, but this cannot be guaranteed. Fees are not refundable.
(If I have to miss a lesson, I find a mutually convenient time to make up the lesson or issue a refund.)
One month's notice, or payment in lieu of one month's notice, is required.
In the case of adults able to come during designated weekday mornings, I have some scope for flexibility about payment arrangements.