If you have a hire car, FNAC, the huge French Multimedia, IT and Book Store at the "Algarve Shopping Centre" at Guia near Albufeira, has a large selection of English language books from Pratchett to Pascal.
To get there, head from the A22 motorway from Tavira in the direction of Faro and continue until you come to the IP1 Lisbon/Albufeira off-ramp.
Follow the signes for Albufeira and after +- 150m follow the off ramp in the direction of the EN 125 to Guia.
Algarve Shopping is about 1,5 km down there. Follow the signs.
Note that the cinemas there, often have movies on in English with Portuguese sub-titles. However, most kids movies are dubbed into Portuguese.
