How much heat do you need? We've renovated a row house in the Netherlands - very similar climate - with solid foam insulation and triple glazing. Haven't gotten to installing a heating system yet. Even in the current cold period it's perfectly fine indoors with a cheap hoodie on. If I didn't know it would make the place unsaleable, I'd be tempted to move forward without any room heating system at all, only a small on-demand water heater.