Welcome to BYC!
I would suggest bringing locks and latches with you from here in the US. I'd go to a higher-end bike shop that sells Trek and Cannondale bikes, etc, and will sell locks that are bolt-cutter proof. You can probably find them on
Amazon.com, too, just check the reviews. Next step would be finding latches they can thread through, but then someone can always just unscrew the latch, so it'd probably be good to put the lock around the actual gate itself or with a chain. Maybe even use chain link fence in addition to hardware cloth so no one can just cut the hardware cloth and take the hens.
To secure the actual coop, I'd again get a big heavy chain and the bike lock and secure to a permanent fence, cemented ground auger, or building when it's not under a watchful eye.
For a moveable coop, I'd search "chicken tractor plans" on google. There are a lot of options out there. Here's one
ConvertiCoop, also called Chicken Arks, but I think they say it fits more hens then it does. You could always make a fleet of them.
Here's some more:
https://www.backyardchickens.com/t/219819/chicken-tractor-plans
https://www.backyardchickens.com/a/chicken-tractors-mobile-chicken-coop-designs
I hope this helps! Wishing you the best in your travels and with all you're doing for the orphanage.