I normally use the ticket office or buy on board, (my local station has no purchasing facilities), I sometimes collect advance tickets booked online from a TVM, but the cheap advances on my regular journey seem as rare as hens teeth.
My journeys usually involve splits, some of them suggested by booking office staff, so using a TVM is not an option,(unless the split is at an interchange and you have enough time).
I live in Northern land and am dreading the installation of a TVM at my local station, on one of my journeys the train departs at 09:25, so I get an Anytime ticket to the next station , then get an Off Peak from there, (originally suggested to me by the guard, that's how I first learned the benefits of split ticketing), I doubt this option will be available from a TVM.
Yorkie mentioned problems at Sheffield station, I was there last week, again buying split tickets, the staff member who served me could not have been more helpful, joking with me that I had done my homework!