Travelling back to Spain without TIE card

Has anyone had actual experience of returning to Spain from the UK with just their passport and the letter from the immigration office showing they’ve applied for their TIE? My husband has his TIE appointment on 20/12 but we are booked on the Santander ferry on 19th January so that we can return our English car to the UK and then we’re flying to Iceland for a few days and returning to Spain early February. We are concerned that the card may not be ready to pick up in time as they say to allow 30 days plus there are all the holiday days to add potential delays. We’ve been looking at getting an autorización de regreso but trying to get an appointment is as hard as it was to get the TIE appointment!! I just wondered if anyone has had actual experience, no helpful guesses please! 😃