Has anyone taken the train and how difficult is it to get frome station to the camp? Or any other ideas.
RS suggests the bus from the Krakow bus station may be a better option than the train. This appears to be the schedule:
https://www.lajkonikbus.pl/krakow-oswiecim.html
As for trains, there are PKP trains, but also trains operated by a regional line:
https://kolejemalopolskie.com.pl/en/home-page
However, I was there today, with transportation and admission ticket provided by Discover Cracow (bought at least a month ago). The bus ride (30 person Mercedes mini-bus/oversize van) was 90 minutes each way, and I started to wonder whether the train had an advantage in terms of travel time. But then you need to get from the train station to the site.
Note that you will be on your feet virtually continuously for at least three hours, walking on uneven pavement, up and down stairs, and for today, at least, dodging puddles. We were told that we'd cover three kilometers at Birkenau alone. So it's physically demanding beyond the emotional toll. And we didn't have to deal with the logistics of getting to/from - just showed up at the meeting place at the appointed time.
Edited to add: If demand is high in the middle of April, it can only get worse as the tourist season progresses...