I believe that with the consumption costs, it is all nonsense, this calls for larger energetic measures. Why not install oil/pellets and radiators? Especially in buildings with basements, it is not such a big deal. I myself live in a rented house and have experienced the renovation phase (previously night storage heaters). With your consumption costs, it pays off after 10-12 years. Subsidies not yet considered.
I would also recommend infrared heating for temporary additional warmth. For example, infrared heating panels can be covered with quite attractive films or pictures. Or you can choose an infrared mirror for the bathroom. We ourselves use a panel from Trotec in the bathroom. It is relatively inexpensive and looks nicely neutral. As a long-term solution (once the changing table is no longer needed), I would then consider more extensive energy renovations. Best regards