Section 3 of the UK HMRC [https://www.gov.uk/guidance/vat-when-you-supply-services-or-goods-to-charities-notice-70158#section3|VAT Notice 701/58] states;
In what media can charities advertise VAT free
Any medium which communicates with the public.
Charities are not required to register for VAT for this benefit, they simply need to prove their ((Charitable Incorporated Organisation Status|charitable status)).