TAP does not have an arrivals lounge at BCN (or anywhere else for that matter), and Star Alliance lounge requirements are that departure lounges are for people holding a same-day departure boarding pass. So that will not work for you.

You could try to access one of several PP lounges in T1. As you are arriving from a Schengen country you mix with departure passengers. But the entry requirements for these also include a same-day departure boarding pass. I have always been asked for one at BCN. So I doubt that will work. There is, I believe, one lounge landside that may not be as strict, but I don't know if this lounge is open, or has showers, or whether if it does, these are free of charge.