Hi.
If the supply is of goods then there will be an import requirement at the borderand so VAT would need to be paid to HMRC via the shipping agent.
If the oversees seller is supplying services to a non VAT registered business then these services would normally be subject to the reverse charge and so there would be no VAT to pay by the UK business but it would go towards their turnover for VAT registration purposes.
Please see the guidance below:
Reverse charge