Your figures are all good and yes I normally germinate them with gentle bottom heat, the thermostat set on 16-18C which means the compost temperature is about right, a little lower as some warmth is lost before reaching the modules. But one can never be that precise and these figures are to give an idea rather than to be followed slavishly, so don’t worry if temperatures vary, as they do, and your seeds will certainly appreciate some warmth in the coming days.
OR you could wait and sow them as late as mid February and in view of conditions now I would recommend that, and the same for lettuce and beetroot. Most worthwhile sowings undercover at the moment (in my opinion!) are spinach and peas for shoots.