I think you're looking for a countdown timer, like other people said just get a normal on-off type and leave it on, then plug it into this thing:
https://www.amazon.com/Century-Digital-Countdown-Repeat-Function/dp/B01D3QEK4E
Although this one probably fits your bill of a "physical dial"
https://www.amazon.com/dp/B00MVDTEXS?th=1
These are US-type, sorry if you're a eurotard.
As for the space heater itself, this one was issued to me by the army over 15 years ago and still works fantastic. It's got a switch in the base that turns off it flips over.
https://www.amazon.com/Dayton-Electric-Heater-Safety-Features/dp/B01IFK28JW
US. Thank you.
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