That is a brilliant question, but it seems at the moment as if we do not actually have an answer to your question! Because, based on the list on Wikipedia and the list in the IP Address Guide presenting the different broadcasters of the Euro 2016 to be played in France next year in June and July there are no broadcasters listed for Spain.
That does not mean that Euro 2016 will not be broadcasted in Spain, but it means that it might not be 100% sure yet which TV channel will actually broadcast the tournament. However, as you look through the list of Euro 2016 broadcasters you can notice that it looks very similar to the channels that broadcasted from the World Cup in Brazil in 2014, and if that is true, then the Euro 2016 will be broadcasted in general by Gol 1 ( a Pay TV channel), but some matches, at least those in which Spain play and some more will be broadcasted on free Spanish channels such as Telecinco and Cuatro.
There is therefore no need to worry, and if you want to watch the Euro 2016 with English speaking commentators instead, then you can of course watch all the action live on BBC and ITV in the United Kingdom, just like during the World Cup in Brazil in 2014. If you click the links you can find out more about how you can watch the mentioned channels in the UK live online, also in Spain!
With yesterdays matches the teams qualified for the Euro 2016 is also ready, so now we just have to wait for the groups to be ready in December and then we can start preparing for the highlight of the summer in 2016 which will be the European Championship in France.