Stephen, been thro the same experience mate, email me if you want.
Tell your accountant. They must have their own equipement and pick the method and time of doing the work you supply. Also their own PL insurance. I was paying £10/hour. It later became X ammount for completing a set ammount of work which was an incentive to both of us. pm Texas Lady she helped me a lot
It cannot be their main scource of income so maybe 1-1/2 days per week. Get them to sign and get witnessed a contract to look after your safeguards.