Strictly, it is an obstruction if you park on a road. Nowadays, action will only be taken if it can be proved that someone was prevented from making a legitimate journey, and this would include reaching their property. The dropped kerb has no legal significance, but it could be used to indicate that you should have noticed that access would be required to the property.
I would not recommend moving the car as recommended above. I have known people to be prosecuted for taking a motor vehicle, and using it without insurance (even though the vehicle was only being pushed). I don't think the law has changed since then.