I stand to be corrected on this but originally in the development of the module I was privy to there was an option to Export out a blank template (you can still do this btw in the version which auto updated as of this morning via > Tools > Generate Blank Excel template) and then from the product drop down in the module select 'Excel' which then gave a file explorer window to Import a copy of the template which had been populated with values. 

Checking the blank template or even the one produced when you click on "Export to Excel" there's a note stating:

"You must use a formula to bring your box values from other Excel worksheets - HMRC don't allow copy/paste or manual entry."

Either the license for Excel is purchasable or the functionality which was originally envisaged is no longer the reality.

I can't seem to find any documentation on the intended usage of this option either which doesn't help

@Ian - Sage article 43136 has been updated recently to clarify Excel as a source of data:

http://ask.sage.co.uk/scripts/ask.cfg/php.exe/enduser/std_adp.php?p_faqid=43136&p_pv=1.584

However the article also mentions this:

Which hearkening back to the builds I saw allowed end users to calculate Non-GBP base values into GBP and then import back into the module. So unless we are just missing a license for Excel that functionality to accommodate non-GBP base currencies will also no longer be possible.

I stand to be corrected on this but originally in the development of the module I was privy to there was an option to Export out a blank template (you can still do this btw in the version which auto updated as of this morning via > Tools > Generate Blank Excel template) and then from the product drop down in the module select 'Excel' which then gave a file explorer window to Import a copy of the template which had been populated with values. 

Checking the blank template or even the one produced when you click on "Export to Excel" there's a note stating:

"You must use a formula to bring your box values from other Excel worksheets - HMRC don't allow copy/paste or manual entry."

Either the license for Excel is purchasable or the functionality which was originally envisaged is no longer the reality.

I can't seem to find any documentation on the intended usage of this option either which doesn't help

@Ian - Sage article 43136 has been updated recently to clarify Excel as a source of data:

http://ask.sage.co.uk/scripts/ask.cfg/php.exe/enduser/std_adp.php?p_faqid=43136&p_pv=1.584

However the article also mentions this:

Which hearkening back to the builds I saw allowed end users to calculate Non-GBP base values into GBP and then import back into the module. So unless we are just missing a license for Excel that functionality to accommodate non-GBP base currencies will also no longer be possible.

That's about as far as I'd got with the new version, there seems to be an excel file created & a mightily well styled one to, but since there is no way of importing anything back in there didn't seem any point to it - unless as you mention there is an Excel adaptor that there seems to be no information on - I await a reply from someone at Sage as I'm sure they monitor these posts