I'm not sure if Access can provide you with the information you are after in this case as I am not experienced with it. The V_reports tables are there to provide a reporting fuunctionality reporting tools such as Crystal reports/Business Objects.
If you do not have this tool or are not confident in its use then I might suggest OVPI, HP's own reporting tool for OVSD.
this has many built in reports specially developed for OVSD.
should you wish to go down the Crystal/Business Objects path then the V_Reports tables are the way to go as they will save you quite some time in both development and SP upgrade compatibility.
Regarding your comment about Crystal and BO, it is possible to pull out all of the required data.
The Service Desk reporting tool my company develops (Report Manager) makes use of Business Objects. We do claim to be able to pull out any data that is stored in Service Desk.
Specific to your original question on Workgroup reporting, our tool provides out of the box funcitionality to report in this way. Basically you need to create a report/query that pulls history information for each call that meets your conditions. This history informaiton would then be run through a set of functions that calculates the amount of time spent by each workgroup.