I just have a bed with a ton of pillows, a few layers of blankets, and a comforter. After 10 minutes the bed is nice and body warm.
Used to be more extreme when I was younger, since I'd build little "nests" out of my pillows. Something about be covered on all sides was comforting.
For a good part of high school I'd cuddle with a long pillow at night, but since then I just have a bunch of blankets and pillows.
Along with my pajamas that I wear on and off, don't need a heating pad or hot water bottle. If anything it would be another distraction when trying to sleep.