I'm an experienced teacher/tutor and tutor as a business ( ie I declare my earnings and am s/e.)
I ask for half a term's notice when parents stop lessons, as I always have a waiting list and this allows me to give waiting parents an idea of when they can start.
My parents know that I need half a term's notice but they don't sign anything- I give them the info when they start and it's also on each invoice every half term.
This means that I have no real evidence that they have signed up to my terms if they suddenly leave without due notice.
Any tutors who have a formal contract? and if you are a parent would you feel comfortable about signing a contract like this- it's no different from extra lessons in schools for music or lanaguages where half a term's notice or payment is required