Hello Rebecca, and thank you for posting to our community.
Based on our information regarding VAT and the Royal Mail handling fees in the link below, it would appear that the handling fees are not inclusive of VAT, since they are charged by the Royal Mail specifically.
Unfortunately we don't currently have a packing slip variable available to calculate your VAT fees based on the shipment value, but our community has considerable influence on the course of our development. The more interest we see for certain features or variables, the more likely they will be added to our app.
Would you consider reposting your specific needs and interest in a VAT packing slip variable, to our Feature Requests forums? These are monitored by our CEO and Product Team and used to prioritize future development work.
We look forward to seeing you in the Feature Request forum and taking an active role in helping to shape ShippingEasy!
Thank you and happy shipping!