Travel / Train trip from CZESTOCHOWA to KRAKOW [2]

Hi. I need to go by train from Czestochowa to Krakow (on August 13th at lunchtime). Should I book a train ticket some days before or may I buy it directly at the train station? I mean: do I risk not to find a ticket the day of the departure? Secondly how long does the trip take? How much does it cost?

Thanks