3 Phase dedicated mains supply

Yes you could but then you have to run the rest of the house on the remaining two phases.

As mentioned above in France it is extremely difficult to run the whole house on the three phases without careful balancing and timing of heavy power items such as a kettle, oven, electric heating.

Thanks Andy, we should have more than enough capacity on the other two phases.

My parents run their house in Cornwall, of similar age and size, on a two phase supply only. And that includes some hefty storage heaters.

Thank you Richard for moving this to the Lounge; a more leisurely repository for mulling said topic.