Great tit fledglings in loft

It seems like some great tits have made a nest in the space under the tiles of our roof, but within the internal cladding of the loft space. Today, we heard chirruping and found that 2 fledglings had got into the loft itself, probably through a rip in the cladding.

They are fluttering around in there and I don't think there's any way they could get back up through whichever rip they got through and back into the nest. 

Any ideas? Should we try to catch them if we get the chance?  We've left the loft flap open, and the bathroom door and window hoping they find their way outside somehow, and then that the parents find them....