Work permit expires, what then?

Hi there,

I was wondering if any of you know, what happens when the work permit runs out, if we then start a 90 days period again or if one is expected to leave the Schengen area for 180 days, unless a request for a new permit is in process?

My work permit expires in September and I'm trying to plan beforehand what action will have to be taken then, as I wish to go to Finland and study there for 2 months or so, before moving back to either Berlin or UK.

Thanks!