WooCommerce now have a built-in product export tool. The problem, for Linnworks, is that any all the product image URLs are exported in to a single column and separated with a comma. Having chatted to Aleksandra on chat, this will not work with the Linnworks import tool.
Given that WooCommerce is a supported integration, it would be great if you could support the official WooCommerce export CSV. Again, just to clarify, this is *not* a plugin - this is now part of the WooCommerce core software.