completely unrealistic, 200 m², double garage nice and all, but what for, if the kids move out only 2 people live together in that huge place, whether it makes sense is another question. Your husband can, if at all, work on weekends/in vacation. How do you imagine that, he works 8 hours on the construction site and is supposed to work after hours as well or what? :D Anyone who hasn’t saved a cent of equity so far and sees no reason to save, and suddenly wants to put aside €1800/month? :D This will end up being a 120%+ financing...
