Roy, next time you're in Spain, pop in to that Small shop thats sells all the things for the beach, you will see the sun glass's there and at the side you will find all types of reading glass's. just try one or two read the little card, to see which is better for you and now you have them..
but I was surprised when I was in the bullring, there was a stall selling hands free phone connectors, cost 5 pounds ( € 7.-) which plug into your cigarette lighter in the car, and they work, over here the same thing cost over €50,- and up) so its a case of swings and roundabouts....