Dear all, could someone help in how to find either a school or someone who could help in the preparation of the GMAT in Warsaw (Poland)?
Thank you very much in advance :)

google search

kaplan gmat test

you can learn gmat online

I did a quick google search but couldn't find anything specifically in Warsaw, or in any of Poland for that matter. Like the previous response said, you might try one of the online test prep services. Also, you might look at online classifieds (craigslist, etc.,) for tutors.

Should be online prep classes, right? Or buy a book + digital materials.

www.readysteadyenglish.com

Possibly the first and only exclusive GMAT and TOEFL private study service in Warsaw with a native teacher.