We got a heated mattress pad last year. It is so nice. Each side has its own controls and timer. Does make it even harder to get out of bed on cold mornings though!
Honestly, it levels up going to bed so much. You tale a showed and come into a prewarmed bed. It's so lovely and so much more effective than a hot water bottle. Easier too.
The key to getting out of bed in the morning is to set the timer well. I usually set it to ~1 hour after I expect to be asleep, so I don't wake up sweaty in the morning.