As far as I know, since they are not a Schedule 1 Listed species (protected at all times under the WCA) and not nesting (all species then protected), I doubt the Law will be of any help. Others may know different of course. (If it were a Bat roost, that would be different!)
I wouldn't worry too much, they'll just relocate anyway and it sounds a very small roost in the bigger scheme of things. Bamboo isn't a native species, so no great loss there IMO, perhaps something more beneficial to birds/insects will be planted in it's place
