Unfortunately I am nowhere near you (Costa Blanca), but can pass on the benefit of my experience with the Spanish system. Like you, we don't live in Spain, but have a place there and we usually go for 2 months at a time when it's neither too hot, or too cold. You do not mention how long you are likely to be on Warfarin, how long you are going to be in Spain or the test frequency. I have been taking it for 33 years and have been subject to regular testing all that time. However, as I get older, I get less stable, so I cannot go for 2 months without a test like I used to. I did try to get the INR test done on the NHS in Spain, but was defeated by the bureaucracy. The village health centre sent me to one in the nearby town, who told me to apply for a SIP card. They do not accept the EHC except for emergencies, but may do at the hospital, I could not be bothered, so I went to the local private clinic where they charge 20 euro's for the test and 20 euro's for the dosing advice. Unless you are experienced at it, you may need the advice and some places are not happy to do the test without reviewing the dosing (so 40 euro's a pop!).
When I got back to the UK I bought a Roche Coaguchek XS on a deal through Anticoagulation Europe (UK) at www.anticoagulationeurope.org/ . It costs about £300, but some health authorities do it for free and after a bit of pushing, the test strips are also available on the NHS. It's an excellent device and now I monitor the INR myself with great success. If you are likely to be a long term patient, you might like to follow my example. You can also become a member for £9 pa and get 4 editions of their magazine the INR Review, which I found most informative. If you want any more information please let me know. Can you PM me yet? If not post here without too many details and I will try to get in touch with you.
We are off to Spain on Sunday from Portsmouth (wind allowing), but I can pick up messages there as well.
Mike