Documentation required to drive back to the UK from Almeria

NOT SURE OF OFFICIAL RULES BUT UNTIL UK ALLOW PEOPLE FROM ANYWHERE IN THEN IT WOULD BE NO GO. BUT AS YOU SAY THINGS ARE A CHANGING BY THE WEEK AND HOPEFULLY IT WILL NOT BE LONG BEFORE FREE TRAVEL IS ON THE CARDS AGAIN. GOOD LUCK.

Totally and utterly incorrect.  If you are a UK citizen you can enter the UK. It is that simple.  

You need to follow the rules set out depending on the traffic light colour of the country/ies that you have travelled from.  That means if entering the UK from either France or Spain (both amber) you need to have a test (not necessarily PCR) less than 72 hours before you leave the country you are in for the UK, you need to quarantine (in your own property) for 10 days, and you need to buy the government's PCR test regime which means a test on day 2 and on day 8 of your quarantine.

Entering from Spain to France adds a complication because you need a negative PCR test less than 72 hours before entering France, so if you want to use the same test result for entry into the UK then you have to get your skates on.

Obviously situations are changing, so I very much doubt that the same rules will apply come July.

This reply very much goes along with what i had gleaned from current information, as you say the problem is going through france as well as Spain , maybe getting the ferry from Santander, bit expensive but takes 24 hours, bit concerned about quarantining as i do not own a property in the UK anymore , seems a long quarantine period for people who have had both vaccines and get tested before we arrive in the country ?

The quarantine (as things stand) is wherever you are staying, so if not in your own property then in whoever's house or hotel your choose to stay.  The point is you don't have to book the government's imposed quarantine, you just do it yourself and it's up to you to obey it ....

I have also concluded that at present it is better to get a cheap instant test locally (I get mine in Huercal Overa, but I think there are many options) then drive to Santander for the boat.  If the boat costs a little more that is offset by the cost of the PCR test(s) you would need to go through France.  It is not as easy going the other way as you need to have your test <72 hours before arriving in Santander, and I find driving through France better.