Not true, MrBounty:
"The Act also enables the Council to issue PCNs to vehicles parked across private driveways, both within and outside Controlled Parking Zones, at the request of the occupier of the property"
http://www.wandsworth.gov.uk/Home/Environmenta ndTransport/Parking/parwhatsnew.htm
Anyway - you can park where you like providing there is no restrictions in force and there is not a dropped kerb. You have as much right as your neighbour to park outside his house, just as he can park outside yours.
He may not need planning permission for the garage, but the council should authorise the dropped kerb. My neighbour's garage is huge - at least 5 cars wide with a pitched roof that has dormer windows, but it didn't need PP.
If he hasn't got the dropped kerb yet he is breaking the law by driving across the pavement. You wouldn't necessarily know if he had applied for the dropped kerb in the proper manner.
If there is a dropped kerb, you shouldn't park across it