Are you sure you need a sick note?
Employees only need a doctors’ note (now called ‘Fit Notes’) for illnesses lasting more than seven days.
This government web page explains more, and also has a link to a downloadable self certification form.
Please don’t request sickness certification for illness lasting seven days or less.
eConsults are switched off at weekends and bank holidays; they are also switched off on the last Wednesday of every month from 11 am for training, but you can still use the service for self-help information.