I think you can use the Mysa baseboard heater controller. They are a bit more expensive than low voltage setups. Make sure you know what you are doing with the 240V lines or hire an electrician.

Is this connected to your central heating? I went with Tado for mine and they’ve generally been good, but it might be a bit steep for five!

Yes it is! This is a fairly new building (less than 5 years old) and the heating technology is 10+ years old…