Compare two Excel tabs and summarise to a third tab

Every month I will paste many rows of data into columns A to F on to the relevant month tab in excel Jan, Feb, Mar etc., always in cell A1
I need to compare a date column - say column F from current month tab with the previous month column F where cell A1 of this month is equal to cell A1 of the previous month

In a separate results tab, I need to report the entries that has no dates to compare in the last two months where column F didn't have any dates to compare

Once I get this results list, I need to summarise the results tab a bit more to give a high level count of how many entries were there, what months have been compared and extract the first 6 alpha-numeric values from a specific cell.

This needs be done with as little VBA as possible and using only formulas or pivot tables if possible and using the refresh all button in excel.

This is an urgent job and needs to be ready by about Monday or Tuesday of next week as a first draft...