I would start by getting a clamp on ammeter and measure your actual loads as you live normal. I think you may have more power available than you realize.
You still may want to charge at 240v to keep the load balanced. The charging spec goes down to 6 amps if needed.
Openevse is easily adjusted. https://www.openevse.com/stations.html
Thanks for the tips. I do have a problem that the house main fuse trips now and then. With only 40A = some 8kW practical max, house trips if I put on oven, toaster and air condition at same time. I can simply flip the fuse back again, so no big deal. But you are right - I need to check the amount of amps really used for various things, never thought about the clamp meter - good idea!
The OpenEVSE is interesting, it certainly has what I would want, but I can't find the products in Europe and importing from US is too much hassle, customs, duties, delays. I found one half-DIY in the Netherlands, but that didn't have the full Wifi so I would need to connect a terminal, that is too geeky and messy.
I can probably use any European charger, set to 16A max and 1-phase. Then turn charging off when using more stuff in house. But it doesn't let me tweak to more amps say overnight when house is idle. I might settle for that solution in order to get nice design, wifi etc without any hassle. I prefer this one (from quality and design points):
It can be set to a number of different steps of charging amps, but only from the manufacturer (messy). Must call them, they access remotely and change. Apparently not available in the app for the user to do himself. Not ideal, but I like the rest. I particularly like that it doesn't look like a snake pit of DIY cables from Radio Shack. There aren't many boxes with nice designs out there.