I regularly receive complaints about cars obstructing residents drop curbs. This can be very annoying and time consuming for residents. Having to find the owner of a car which is stopping you from either going out or arriving home in your car is not a very pleasant experience. It can also cause a lot of ill feelings between neighbours.
I would ask all drivers not to obstruct of overhang drop curbs and not to park over disabled drop curbs either.
If you do find yourself being blocked in one option you can take if really needed is to call the police on 101 and explain the situation to them it is an offence to obstruct your drop curb.
If it is your neighbour who is obstruction your dropped curb the best way to deal with it if possible a quiet word in the first instance.