Deltanex,
Going to 3 phase should provide nothing but benefits (except for the initial investment), and will probably increase the value of your home.
Chas,
I shouldn't have missed the European standard one phase 220v. This makes a difference in amps needed for some things as Watts = Amps x Volts. So, you're right about the 80 amp example - making this a bit more minor.
Vinny,
If a 40 amp breaker does not trip at 40 amps, then it is not functioning correctly. A 40 amp breaker is designed to trip due to the heat created at 40 amps. Anything over 40 amps is a potential hazard in that case. That's why we use the breaker - for protection from damage, fire, electrocution. If a 40 amp breaker allows 45 amps, your safety is not functioning correctly.
All things considered, an upgrade is most likely the best total solution.