A few points...
"...if your house (most UK houses have this) has a 50A main breaker."
This is news to me (as a qualified electrician). The most common rating for the "service fuse" is 100A, though some smaller properties such as flats do have 60A.
"The Coronation Street adverse effect is I presume known..."
Indeed - the electricity distributors are quite interested in the bonus they will get with electric cars. When smart metering is rolled out, there is likely to be a provision added to temporarily turn off the charging for your electric car. What this is used for is when there is a demand surge (or a drop in supply such as a station shutting down without warning or a dip in renewables) a number of car chargers will be turned off for a few minutes while fast-reacting generators are started up. At the moment companies sign special contracts to allow some of their systems to be turned off for up to 20 minutes for this purpose. There is also serious talk about building systems where you can sell back some of the power in your car when the grid needs extra (you could have a switch that allows this to drain you down to 80% or something).
"Note just under 19 cars require a MW of power - one 1MW capacity wind turbine in the UK provides on average 24% of capacity. - so 19 cars need provision of FOUR medium sized Wind Turbines"
This would be true... if those 19 cars are being charged 24/7. Chances are that you could charge significantly more than 19 cars with the output of one 1MW wind turbine. And as stated above, the electric cars are perfect for smoothing the uneven generation wind turbines can give.