I know this is a bit late but I was wanting to achieve the same result. A excel spreadsheet with a list of all my group policies so I could keep good documentation on them plus carry out housekeeping tasks.
Due to the export list being unavailable in the GPMC I found that if you carry out a search within the GPMC you can then save the results to a CSV. You need to carry out some tidy up work on the spreadsheet but it saves alot of time!!
Hope this helps