Can i claim business mileage to and from a 'home office' if i am not paying rent? I am obviously not claiming for the home office, but unsure how to count mileage.

I work in youth sports. My role combines coaching on the field with admin tasks in the running of the club I work with - website management, club communications, setting up programs, etc and as such I spend most of the day working from 'home' before traveling to field sessions in the evening and weekends. I don't however pay rent where i am living and thus don't claim a home office deduction. If i was paying rent on a place myself, i would likely have a separate area set up and consider that a principle place of business, and therefore feel i could claim my journeys too and from field sessions as mileage. Though please correct me if that's wrong. 

Since I am using 'home' for my day time hours, can i still treat it the same as the above example and claim those business miles? Or would they simply be my commute since i cant claim a home office? Most of my field hours are in one specific town, albeit it sometimes with travel between fields, do i have to claim my first and last trip as the commute even though i spent the day at home working too? 

What about if on a saturday i am not doing 'desk work' first and just go straight to the field for a game? is that a commute? 

Occasionally i do other on field work with other clubs or programs. Would a drive to a more random location for say a one off session be business mileage or a commute?

Thanks in advance for reading and any responses.