Sub Test()
Dim oCCS As ContentControl
Dim oCCE As ContentControl
Dim lngDays As Long
  Set oCCS = ActiveDocument.SelectContentControlsByTitle("Start").Item(1)
  Set oCCE = ActiveDocument.SelectContentControlsByTitle("End").Item(1)
  MsgBox fcnCalcDays(oCCS.Range, oCCE.Range)
lbl_Exit:
  Exit Sub
End Sub
Function fcnCalcDays(Date1 As Range, Date2 As Range) As Long
Dim lngDays As Long
Dim lngIndex As Long
Dim dTest As Date
  lngDays = 0
  dTest = Date1.Text
  For lngIndex = 1 To DateDiff("d", Date1.Text, Date2.Text)
    If Weekday(dTest, vbUseSystemDayOfWeek) <> 6 Then
      lngDays = lngDays + 1
    End If
    dTest = DateAdd("d", 1, dTest)
  Next
  fcnCalcDays = lngDays
lbl_Exit:
  Exit Function
End Function