One of the things that I like about my teaching job is that they build in non-teaching time for doing prep and marking - so I get a whole day (or two) each week where I can attempt to catch up with myself - I never do, but I keep it moving along. I always make a list to work to and cross it off as each is completed; and I aim at 'good enough' only (perfection disappeared years ago). My boss is good at problem solving, so I always approach her if I get stuck and thankfully she is supportive rather than judgemental.
Maybe you could organise a non-shop work day that you use solely to get some things done? I imagine customers would be as distracting as students