I have a workbook that I use to keep track of numerous projects which are identified with a cost code and a sub component part.
There is a master worksheet which contains all the code/sub codes, this is used for a drop down on a setup sheet to define your own projects from the master list, this was done as this might in my case become used by more in the department and then I will look at updating the master list externally but that is way off at the moment.
There is a worksheet for each week where you can specify the code/sub and a description from a drop down list along with the time interval in 15 min slots.
The time for each code is summarised on that sheet, there is also an overall summary sheet which gives the amount of time spent on a project as the weeks go by, just in case the managers ask.
I am putting the finishing touches to this, but you quite welcome to what I have as is and customise it as.
If you send me a PM (personal message) with your email address I will send you a copy in the next few hours.