On the 31st of January 2020, Britain has officially left the EU. Luckily, the two parties were able to reach an agreement which now allows the British citizens to exchange their driving licences to Spanish ones until the 31st of December 2020. It is only starting the 1st of January of the next year that the transition period would come to an end. From then on, the general regulations, applicable to the third countries (non-EU), would apply to the British citizens as well.  This includes that:
a) It would no longer be possible to exchange British driving licences to the Spanish ones
b) Citizens with British driving permits would be able to drive in Spain for the first 6 months from entry OR from the date of obtaining their Spanish residence
According to the official British government website, “visitors with a non-UK driving licence are able to drive in the UK; you do not need an international driving permit (IDP)”. However, it might be subject to changes as the transition period progresses and the negotiations continue.
If you intend to reside in Spain for more than 6 months a year, it would be wise to exchange your driving licence to a Spanish one this year, that is, during the transition period. Otherwise, you would be required to obtain a Spanish driving licence from scratch. This means attending the lessons, passing theory test in Spanish and a practical driving exam with a Spanish examiner.
In order to exchange your driving licence, you need to meet some requirements. For instance, you need to make an appointment at Traffic Department and fill out this formYou also need to pass a psychometric test. And, in addition, you would need to bring along all the required documentation to process your application:
a) your ID (either passport or ID card or your residence card)
b) your driving licence
c) the proof of fee payment (Tasa 2.3)
d) your recent photo of 32×26 mm