Freelance daily charge

Firstly we calculate the billable days in a year.

The days we're not working are:
 140 days of weekends
+   8 bank holidays
+ 30 vacation days
+   5 sick-days
+   2 emergency day offs
------------------------
185 days off.

So the billable days are 365 - 185 = 180 days per year.

According to my working experience I would charge 1,000 pounds per month which is 1,000 * 12 = 12,000 per year.

12,000 / 180 = 66,7 pounds per day would be my daily charge.