Ok was up lots in night (twice with DS, mostly worrying about Ofsted) and managed to sleep through alarm and doorbell to miss parent dropping their child off.
I feel awful about it and its worse as I havent' had them long so they won't know I'm usually reliable.
Oh well, have offered parents a free day to make up for it so hopefully it'll all be ok, but it feels miserable now. Think will be off to buy a 2nd alarm clock today!