As of 1st July 2021 for B2C transactions supplied from outside the EU, the supplying company is now liable to pay any VAT due. They should charge the customer their local VAT and pay that via an agent registered in the EU. This VAT is paid via the Import One Stop Shop system. You can find more details about this from the EU or Royal Mail here:
https://www.royalmail.com/import-one-stop-shop-ioss
https://ec.europa.eu/taxation_customs/business/vat/ioss_en
When a customer places an order with a shop outside the EU that is being delivered to an address in the EU the shop should pay the EU VAT for that order. Some points on this:
Taxamo Assure is a new service from Vertex, it allows you to make Pay As You Go IOSS VAT payments. They act as the company registered with the EU for paying your IOSS VAT charges.
You integrate the solution into your own shopping cart, when the customer places an order you pay Taxamo the VAT and then pay £2.00 per delivery. Most other companies charge fixed monthly rates + the VAT.