How long is your flight? If possible, try to time pumping before and after your flight, rather than inflight. I say this because the only possible place will be in the toilet, and that's not the most ideal place as you can imagine. Or you can try asking the cabin crew if they can draw the curtains for you at the aisles but i won't bet on that.
For storing breast milk, try asking the hotel/venue you are staying if they could freeze the breast milk for you. Then when you are about to leave, pack the fbm into cooler bags to bring on board. I actually checked mine into the big luggage. It came back still in good shape. But you must pack it well and tight and completed insulated.
If the flight is too long, it may not be practical to transport the fbm back. But dont't stop pumping. Just pump and throw, so as to keep the milk supply stable. If you find it a waste, you can always use it for self consumption!