Copying monthly expenses

Hello and welcome to the Community, lrobson

There isn't a copy function in QuickBooks Self-Employed. If your bank is supported on Open Banking in QuickBooks, you can connect your account to easily download and categorise transactions. 

As an alternative, if you have a CSV file containing a list of the monthly expenses, you can manually import this each month (after amending any details, such as the transaction dates). Hope this helps!