Just had a call from National Grid who have been excellent. It is a single feed with no issues regards installing a charger. Thanks again everyone.
Great news!
As an aside i got an estimated quote of £1800 to install a three-phase supply to my home.
If having a HP/EV charger/Inerter and you load exceeds that supplied by your existing single phase supply, the DNO will upgrade the supply for free in most cases.