We'll have the same unit and have the same set up with heating only downstairs, though the house is about a quarter smaller than yours (208m2).
UFH set for 21 between 7am and 10pm and yesterday was our highest use yet, using 34kWh of electricity all told (which includes for the usual dishwasher, oven, showers, washing machines on etc). I'm not sure how we find out about defrost settings, heat demand and calculate if our flows are right etc. but does that sound reasonable enough (or not excessive enough to spend my weekend working out how to make the set up more efficient)?