i have about a page of terms and conditions that i adapt for eah job. Covers things like working hours, if we order materials and they cancel they are liable for any re-stocking charges, when payment is due, what happens if there is a dispute, etc etc
It gets sent with each quote. If they want the work done then they have to sign it before the work is done, saying they agree to the quote and the terms and conditions. You also have to give them details about their rights to cancel and how they can do it, as well as that they can waive thi sright if they want the work done asap. Ive got a copy of it from our local trading standards. when i get a chance ill post it up here.
Get them to sign as if you have a problem, it helps to clarify your position