There are unconfirmed media reports that Spain now requires UK tourists to show private travel insurance on arrival or risk fines up to €6,900. This has not been confirmed by the Spanish government or the UK Foreign Office. No official policy has been published. For now, it’s recommended to carry full travel insurance along with your GHIC/EHIC card. We’ll share updates if official confirmation appears.
From Spain tourism website under health.
If you need to purchase medicines or see a doctor during your trip to Spain, remember that emergency treatment is guaranteed. For other cases, we recommend that you read our advice. We also inform you where smoking is prohibited, where you can find restaurants if you have coeliac disease and what precautions to take if you have food intolerances.