I think on most jobs Terms aren't required. Though I think anything over £2k I'd want to quote for formally and include some terms.
Can you imagine waffling on about terms on a splashback job?
I've spotted some members over the years that have come up with a pretty standard invoice that has main terms and conditions on them which could cover you to a degree if the customer starts to try and get out of paying for whatever reason though I think the be all and end all of it is if the customer is the type that doesn't want to pay then they're not going to pay, no matter what you give them before or after the job.