I am learning Python as wel for my master dissertation. I received a code for Datacamp, an online learning platform and this has been a really fun learning experience so far. Since I received a code from my professor I don't exactly know how much it costs, but Datacamp provides you with a lot of interactive fun courses. Unlike a book you actually have to exercise continuously.
If this would be too expensive or not your cup of tea, I recommend watching Youtube tutorials or picking up the book "learning python" from Mark Lutz.