i think a car has to be over 10 years old to be considered for classic insurance. they cat. it as a modern classic. depends on the ins. company really. however, if its a low premium your after classic ins. will not assist unless you restrict the mileage, so if its your daily drive your buggered.
the car also has to have a very high % of its original parts, i.e no aftermarket stuff etc
with regard to road tax the car has to have been built before 1st jan 1973, so even if the car was not registered until 1980 it would still be exempt.
hope this helps..........