In Law, you will probably have right of access and to have the use of your parking area, there may be a building scheme or restrictive covenant in force which may prohibit trade, excessive noise, not permitting right of access or even putting out washing or washing your car on certain days, it is likely if there is on your house your neighbours (in a similar type of property) will probably have similar restrictive covenants that are clearly intended to benefit the area as a whole. The law allows the owners of any plot to enforce such covenants against any other plot owner, even though neither were party to the document that imposed the covenant.
In practice, you will probably not want to go to law and the way forward then is as factor 30 & murraymints say to talk to your neighbour, explain the problem and ask them to cease blocking your access. The law should be the last resort.