How can you keep baby turtles -yellow Belly Sliders- warm and alive while waiting on heat and UVB lamp and supplies to be shipped?

I would put them outside in some kind of container and let the sun do its job, but if the weather is cold, I would put them under an ordinary desk lamp or two. The only thing that makes UVA and UVB lamps different is that they provide needed vitamins. Try giving your turtles supplements to make up for that. If the food is shipping, feed them vegetables, but avoid Iceberg lettuce. Chop up the veggies real fine since your turtles are babies. My yellow belly loves corrots. Of course they are matchstick carrots so she won't choke. Good luck with your new turtles!