I'm specifically looking to fill the cells K2:K10 with the hours J Bloggs would have worked if it weren't a bank holiday.
The screenshot shows J Bloggs working 9.5 hours for three days a week starting April 1st. In October he decides to change his hours to 7.5, five days a week. Finally on the 12th of Jan he changes his hours to 5 hours a day mon-fri.
I'd need the cells in column K to look up the right hours on the right day of the week between the correct dates in A5:A8 (and H2).
Note: A1:A2 is irrelevant here. Also I'm aware the dates I've hastily added for bank holidays are incorrect ones for 2017/18.