Europe on 5 Watts a day

There is a pretty good chance that I will be based somewhere in Europe for a month in September or August. I most likely will be based in Leipzig, Germany. I should have rather gone on an earlier tour so that I could be there in the EU Summer.

I cannot tell a lie, one of the major reasons for me  agreeing to go and work there on a short contract, is to explore the amateur bands from an EU perspective. I plan to take my K2 or the tiny HB-1A along. From past experience, I know operating from a hotel room is not worth the effort due to wideband QRM that is ever-present, but I think operating a small portable station might do the trick? I suspect or hope that the QRP activity will be much higher than what we experience here in South Africa.

I wonder what is required to operate from Germany. Do I simply use DL/ZS6A or must I first seek permission from the local authorities? I do have a HAREC certificate. I might end up in Finland, Estonia, Sweden, Poland or Luxembourg and I don’t feel like too much red tape.

Any help with the above will be appreciated.