Britain has announced the countries on the "green list", those that Brits can visit and return from without the need to quarantine. They would still need to take tests before and after though.
Although the Valencian region would qualify because of the low rate of infection here*, Spain as a whole doesn't. So, as things stand, we will not be expecting friends and family over just yet and we will not be planning to visit them either.
The countries on the list are Australia, New Zealand, Singapore, Brunei, Iceland, the Faroe Islands, Gibraltar, the Falkland Islands, Israel, South Georgia and the South Sandwich Islands, Saint Helena, Ascension and Tristan da Cunha, and Portugal, including the Azores and Madeira.
You can imagine a take up for holidays to some of those destinations however, South Georgia and the South Sandwich Islands are only accessible by sea and there is no visitor accommodation on them.
* 41 per 100,000 - Spain average 202 with a high of 463 in the Basque Country.