Hello Martyn Rae,
Welcome to the Community page,
So when you log into your Quickbooks Self-Employed account, if you go to transactions in the left-hand bar navigations.
select the account> on date select custom and put the date range in you want so, for example, 1st Jan 2020 to 18 Aug 2020> apply> this will then only show the transaction for that account in that time period.
On the far right-hand side, you will see an icon that is a rectangle with an arrow going out when you click that it will export the information out of QuickBooks and into an excel document for you.
If you have any Qs let us know.