A 'right of way' is exactly that. You own it but they, and others, have a right of way over it. We have the same situation in our garden. You (or they) are not allowed to block the right of way, so there would certainly be no parking in the driveway.
Personally, I'd put it in writing to the Estate Agents, to make your postion clear and to ask them to alter their details. It will, or should, all be clear on the Deeds of both properties so any solictor will pick it up and should inform the purchaser.