Just remember that museums, zoo, galeries will not be your daily life, when you stay longer. Well, I do not know your working hours

Try to get a feel for everyday stuff, multiply by 365'000. Notice all the small, and big things you will need language for. You will be lost with those for many months, at least the bigger ones. In case you do have quirks, try to live them here. Try to make things work that are a challenge to the system here (making mobile internet work on my Macbook Air was an interesting experience, way back when i did my exploratory trip

). Notice what already does, or might easily get on your nerves. Consciously. And from another thread, if York was too big already, I doubt that Helsinki is the place to be. If I had to choose a cosmopolitan area to live in, it would be Helsinki, for sure. But I can totally relate, and York seemed rather perfect for my taste

So I would rather check out other towns, not the galaries, to be honest. If it should be exploratory to where you want to live, rather than how to spend spare time in Helsinki, that is.