How to extrapolate weekly data into daily data, taking account of absences

I receive a monthly export of data showing staff rotas and I want to highlight the % availability of Duty Officers on a Role in any particular week, by taking account of any planned absences of staff that are recorded as comments within the data.

I have been able to extract the comments about absences and record them in 2 additional columns giving the date range that this applies to. Now i need to extrapolate all this weekly data into daily data with a separate row for each Duty Officer on each day, with the absences included in the Value column as 'Unavailable'.

This is what the current weekly data looks like:	..and this is how i need it to look with lots of extra rows:

Can anyone show me how to do this?