Dispatch countdown cut off timer

Can someone write us a cut off timer for last dispatch, exactly like this site [login to view URL] The following must be customisable and easy for us to change 1. Change cut off time 2. Add/remove non shipping days i.e Xmas Day, Bank Holidays etc 3. Exclude Saturdays and Sundays as shipping days, option to change this. Example, if cutoff is 17.00 Mon - Fri About to order at 18.00 on Friday, timer would show Order in the next 71 hours for delivery on Tuesday xx of xxxx using our express service. After 5pm on Thursday it would also let the customer know there is an option for Saturday and Sunday delivery like the example above. This would only show after Thursday 5pm and disappear on Friday after 5pm. It also needs to take into consideration, leap years and the 30th day months, we have one at the moment that shows the 31st June etc??? It somehow corrects itself on the 1st July though? Screenshot of one error we have at the moment with it.