Travel back to Spain from UK what's needed

If you full dose of vaccination is longer than 270 days ago, you need  to show  your certificate that you’ve had your booster. No locator form required. 

No vaccination or no booster, then you will need to take a  test before your return and that certificate will need to be uploaded to your SpTH form.

Full information here

We travelled from Plymouth to Santander by ferry two weeks ago and all they asked for was the passports no proof of vaccines or anything like that anymore. 

They don’t ask everybody, it’s a random thing… My wife and I flew into Alicante, she got stopped and had to show her vaccination certs, whereas I stood by her side as she produced them, and I didn’t get asked at all!

I've been to Alicante airport twice this year. I was just waved through the vaccination desks the first time, but got stopped the second time (July) and my certificate logged.

Football in the summer?

Yet again same question. Yes others can tell of their experience, however why not get the “correct” information 

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Thank you for this very concise answer. Just what I need.

Do you know if I would also need to upload the CoVid cert to the airline?

If anyone wants to know how to fill out the SpTH form, this video should help - https://www.youtube.com/watch?v=32vY-WiSVfk

No requirement for the SpTH form, I don’t know about other airlines, but RyanAir give you the option to upload your Covid cert, but it is not compulsory. It’s not the airlines who ask to see them now, on flying back I doubt you will be asked to show it to anybody, but keep a copy of it jist in case either on phone or in paper format

Thank you, I will tell my visitor, who is unvaccinated, to keep their test certificate close at hand. But given that the UK Gov says ...

Travellers from the UK who can either show proof of being fully vaccinated, or of having recovered from prior COVID-19 infection in the last 6 months, or who are aged under 12 years old, do not need to complete Spain’s Travel Health Control form. Everyone else must complete Spain’s Travel Health Control form no more than 48 hours before travel to Spain. See Spain’s Ministry of Health travel pages for more detail.

https://www.gov.uk/foreign-travel-advice/spain/entry-requirements

and RyanAir still sends you to the page to fill in the Spanish Health Form under the section where they talk about mandatory documents, I think it is best for them to still fill in the SpTH. Even though as you say the chances of anyone asking for them for it are very low.