hyvin menee! and suomea suomeksi 1 and 2 are good books. i've used both. the first one i used in finland during a course for foreigners studying finnish and suomea suomeksi i've used in university for my basic finnish courses. they do both sort of require someone to check that your results are correct when you fill in exercises, but apart from that, they're good. :)

a piece of advise: when you come to finland you'll really have to make an effort to use finnish in order to learn it. it's easy to hang out with the other exchange students instead of the finns. if they offer you a tutor/mentor to show you around and be of assistance, say yes - that person is the first finn you'll get in touch with and will be of tremendous help to get you included in finnish circles.