Since the UK has been plunged into the seventh circle of hell and will be there for a little while, I’ve found a workaround for this exact issue which works for me.
I’ve been just wrapping my regular duvet around one part of me, usually my upper chest. I just hold it tight under my armpits and leave the rest of me uncovered. This seems to help somewhat, although obviously isn’t as nice as being wrapped up, it’s still better than nothing. You could do it for whatever part of your body likes the pressure the most. You could even have a couple different sheets, or use a pillow cover for example around your ankles if that helps.
Also, having your feet outside the covers is the most important part as cooling your feet will make the rest of your body feel cooler.
Tbh though, nytol has helped me too. I struggle to sleep at the best of times and nytol combined with good sleep hygiene has helped me get more than 2 hours sleep a night. Nytol is designed for temporary use and you can get it over the counter.