A working day is any day in which construction work will be carried out. This is not just full days of construction work. If you are only planning on working Friday mornings for example, Friday will still be counted as a working day when calculating your working days for the purposes of the notification test.

In the same respect, you will need to count weekends if any construction work is likely to take place. So if you were planning to do a couple of hours on a Saturday as well as working in the week, then this will count as a day towards the notification threshold.