Traffic light conditional formatting with weekends & bank holida

Hi,

I have been asked to amended a set of conditional formatting rules I already have in place, to allow for weekends and bank holidays.
The general idea is, that after I have sent an "MOS" form and entered the date sent into the MOS column (Call this column "A"), this triggers the formulas to start a traffic light clock, please see formulas:-
=AND(E2<>"",OR(E2-D2=3,E2-D2=4))
=AND(E2="",OR(TODAY()-D2=3,TODAY()-D2=4))
=AND(E2="",TODAY()-D2<=2)
=AND(E2<>"",E2-D2<=2)
=AND(E2<>"",E2-D2>=5)
Then after a document was sent back to me, I enter a date in the column next to it (Call it column "B").
So in column C, there would be a figure to show the number of days between the date in A and the date in B.

Is there any way I can edit the formulas above to tweak the clock into NOT counting weekends and bank holidays?

Any help would be greatly appreciated!

Thanks,
Lauren