I found that most of what I expressed was not getting drunk anyway, so I would do one "keeping" express either at lunchtime or in the morning before work, and otherwise just pump and dump wherever I could. You should try and get good at quick hand-expressing of a small quantity so you can manage engorgement throughout the day by just squirting down the sink as needed.
my work had a first aid room and a meeting room available for use, but I was also quite often out and about. Big jackets were very useful - as was double pumping, which was much quicker.
If you have access to a fridge then it is much faster to just put the milky pump bits back into the fridge without washing them.