Help distributing hours over a year

To make this simpler I would change the values in row 10 to dates, e.g. in K10 enter the first date 1-April-2013, custom format as d to show the day only (so it looks the same as before) and then copy all the way across....

.....and then in K11 you can use this formula copied all the way across and down the columns

=IF(OR($E11="",K$10>$F11,WEEKDAY(K$10,2)>5),"",$E11/NETWORKDAYS($K$10,$F11))

See attached where I entered that formula in rows 11 to 15 only