The following update has been published by the British Consulate today for people trying to return to the UK by ferry from Spain:-

Ferry travel

There are currently no scheduled passenger ferries operating between Spain and the UK. We are working closely with Brittany Ferries who may be able to assist repatriating a small number of people on their freight services. If your ferry has been cancelled and you wish to return to the UK, please contact the British Embassy online (link below) stating your name and booking reference number.

https://www.contact-embassy.service.gov.uk/?country=Spain&post=British%20Embassy%20Madrid