Hi pete and ange
This is from another thread and from my experience from after Christmas at home and confusion on xmas/newyear in Spain don't worry!
The Supermarket only opens till 2pm on Sundays and Public Holidays
Good Friday and the Day before (Thursday) are Spanish Holidays however Easter Monday is not.
If you are still not 100% ...... stop at a petrol station 24/7 and they will see you through. Have fun and enjoy!