Distance sales question - EU VAT Tax Advice - Accountant

I currently sell online and I have VAT numbers for the following countries:

UK
FR
DE
ES
IT
CZ
PL

My stock is stored in the UK and various EU countries and sold to customers throughout the EU.

I am under the threshold for other EU countries such as Austria which I sell to.

On my UK VAT return do I need to put down the value of the sales to these countries including the EU countries I don't have a VAT number for (such as Austria) in Box 8?

I have been told that 'Box 8 doesn't need to contain these sales - see the table under point 6.17 here: https://www.gov.uk/guidance/vat-and-the-single-market-notice-725#section6 '