Used car big problem! (London)

Hi,
I've just relocated to London and bought a used car.
I drove back to Italy with my car but it broke down here in Rome and it seems there is no way to fix it.
Therefore I was thinking to demolish it here.

Question: what I should do? To whom and how should I communicate that in London to be sure I'm not still required to pay road taxes and everything?

thanks in advance.
M