I know very little about portugal's (and the iberian peninsula in general) pre roman empire period and would like to know more about the celtic natives that lived there and how they lived before the romans conquered everything. Thanks :)
I would personally recommend "Protohistoria de la Península Ibérica", by Almagro.
I don't know any bibliography in English, sorry. I'm Spanish, and as you can imagine most of the scholarly materials about pre-Roman Iberia would be in Spanish or Portuguese, so I read them in the original language.