@Synchro Vodafone has PAYG options, the cheapest one at £10. You HAVE to disable auto-renew during the registration process, so pay attention to all the options in the form. https://www.vodafone.co.uk/sim-only/pay-as-you-go-sim Not sure if you can register from France though, they do ask for a UK address (not sure what it is used for, because once the registration is completed, you get the eSIM via email). They also require you to provide a "main" phone number, french ones are accepted.