Posted: Thu Feb 25, 2021 10:22pm
Hi Mark you are good to go this should help
On 22 December 2020, Spain introduced travel restrictions on passenger travel from the UK by air and sea. These measures have been extended until 6pm (GMT+1) on 16 March 2021 (5pm / GMT in the Canary Islands), with the exception of Spanish nationals and those legally resident in Spain.
International transit through Spanish airports by passengers on flights departing from the UK is permitted on presentation of a negative PCR, TNA or LAMP test taken within no more than 72 hours prior to arrival into Spain. See Transiting Spain
If you are resident in Spain, you should carry your residence document (the green paper EU residence certificate or the new TIE), as well as your valid passport when you travel. If you are not in possession of a residence document, the Spanish government has formally confirmed to the UK government that UK nationals who were legally residing in Spain before 1 January 2021, and as such are beneficiaries of the Withdrawal Agreement, can present other documents to prove their residence status when entering Spain. See Additional Requirements for UK Nationals resident in Spain for further information.
Good luck Marcus