Travel to Portugal by Bus
Travel into Portugal via bus is available through Eurolines from the United Kingdom and Busabout from all over Europe. With Eurolines, one can travel from the UK to Paris to Lisbon. The bus service visits Lisbon six times a week, but also has stops in other parts of Portugal.
Check the timetable for your expectant travel week.
As for Busabout, this is a hop-on / hop-off service that offers tickets in two-, three-, and four-week increments. Destinations are throughout Europe, with Portugal is definitely on the list.
And finally and not surprisingly, from its one neighbor Spain, there are various bus options departing Madrid, Seville, and Granada.