301 Polish Verbs by Janecki
This is a really good book. Don't let the 301 pages of grammar tables freak you out though.
"Teach yourself Polish" (most good UK bookshops have it) and "Polish in 40 days" (a bit of an optimistic title) are both good books to start with.
dict.pl/dict_iso is a very good online dictionary.
Many people recommend an audio course called "Pimsleur Polish". It's very American in style, but don't let that put you off - the American method of second language acqusition has a lot of good points. One benefit of the Pimsleur series is that you will be speaking from the very first lesson. I don't know where you can buy it in Europe, but since it works well without the accompanying coursebook, somebody unscrupulous might download it from IsoHunt or PirateBay, though obviously that might not be legal. I used their Pimsleur Arabic with some success.
is it possible that there is other dialects in polish
There
are, not there
is, and yes there are dialects, but much less so than in most other major languages.
because i read okay translates to dourbze
You can say OK in Polish. 'Dobrze' (remember that the 'rz' sounds a bit like the 's' in 'pleasure' (think 'pleasure' but change the 'plea..' to a 'dob...' and you're nearly there) means 'well' (as in "I did it well") but Poles often use it to mean OK. "Dobra dobra" is used by some people, but can sound sarcastic or over-jolly, and "spoko" or "spox" is popular with young people, sk8ters etc..
Remember, one less than appealing habit of some Polish people is that when a foreigner uses a Polish word, they'll pretend it's wrong and tell you an alternative. When you use that alternative to another Pole, they'll insist that one's wrong too. Not everyone in Poland does that, but some certainly do. In Polish culture, there's nothing strange about telling someone they're wrong, even if you only think they're wrong (some Polish people will argue that black is white just for the hell of it), and correcting someone's grammar isn't seen as bad manners.