Great Tits nesting in a (very tall) gate post - not sure if the chicks can get out...?

Hello, I've just discovered a family of Great Tits nesting in a gate post. They enter through an old hole where the lock used to be, and dive about 1.5 metres down to the nest, which is right down at the base. I've managed to identify about 6 chicks inside, currently feathered but I think with eyes closed. My concern is that the fledglings won't be able to make it up so high to actually get out of the hole once ready. Should I do something - perhaps crafting a small "ladder" made of rope so that the chicks will have something to cling to during their ascent? Or just leave them be? I have a few photos if you'd like to see more clearly the situation! Thanks so much! Natasha :)