Seen a lot of cabs coming in, it's not very far away from residential/commercial zones, maybe a 2 min drive from the nearest HDB to the farm. So I don't think there are issues with cabs wanting to go in. It is definitely not as ulu as the other farms.
As for exiting, just let the Iwarna staff know, they will help you call cab out.
Sometimes you could even hitch a ride from the hobbyists gathered there.