[peanut]

Use a dehumidifier if things are quite bad, or try those windowsill dehumidifiers - Ansio or the Unibond types works quite well for window condensation.

Opening windows when using the shower or cooking etc helps, not drying clothes on radiators. And try to keep a constant temp in the home also helps.

I have the opposite problem and I have to use a humidifier when I put the heating on.