If looking for something readable and accessible in English, you might want to try ...
Livermore, H.V., The origins of Spain and Portugal. London: G. Allen & Unwin, 1971. ISBN 0049460056
Livermore, H.V., New History of Portugal, 1976 sorry I don't have ISBN
He also wrote two earlier works History of Portugal and a History of Spain in the 60's I think.
He is somewhat of an authority and, if the two contributions he made to Griffith, P A History of the Peninsular War: Modern Studies of the War in Spain and Portugal, 1808-1814 are anything to go by, he is by no means Anglo-centric.
Best wishes
A