My workplace is pretty good in this respect - they have a policy to support breastfeeding by providing a designated place for it & paid lactation breaks. Which they kinda have to have so their reputation isn't compromised by being unfriendly to parents/families.
So there is a lockable "Parents room" which is tricked out with it's own fridge, microwave, sink, cupboards, table, changetable, couple of toys (if you bring kids in) & a comfy reclining armchair with footrest & pillows. Big window to the outside (with blind) but no windows inwards facing.
My manager asked if I would need to take breaks to express & was totally fine with it - I did take them during non-busy times during the day though.
I'm not sure what the legislation is though. Maybe outline to them what your needs/concerns are & discuss how this can be met. A blind or curtain shouldn't be too much for them to consider so that privacy is maintained. Or even a little bar fridge for the room.