Leisha Camden, Skyfire20 and I was in Tampere in 2017 for a the big postcrossing meetup, so I am an experienced Tampere traveller:-)
In 2017 we took a round trip. We started with a flight to Tallinn, Estonia. We stayed there a couple of days, and then took the overnight ferry from Tallinn to Helsinki.
Tampere isn't that far from Helsinki, our train from Helsinki to Tampere took only about 1,5 hours.
The world's only Moomin Museum is in Tampere:-)
(It opened just after we were there.)