POA.
Kinda the definition of PEROID OF AVAIABILITY no? 
I’d personally put it as Rest but I would consider POA if I was on agency.
Mainly to make sure I got paid and them not to try to claim “you didnt actually work”
But I think there is a legislation somewhere that commuting to work has some impact on daily rest if it is over a certain amount of miles. But I can not remember it or find it. So maybe I am talking bs.