I have had a hatch without a hen, took them out to introduce them to the flock. I watched them closely, and in the evening they went to the roost, they had feathers and I left them there. All was fine, the flock accepted them, the rooster tried to be "moma" but the chicks had no part of that! Not a moma!
I do have grates (plastic trays from a bread factory) as landings for those that want to use them. Also a hen did a winter hatch, I was worried, and it took some time for me to be comfortable with 4 day old chicks out in the snow.
I agree with ditching the heat lamp, be safe!