Good Lawyer Guide's response

If it is refused, you can appeal to the Planning Inspectorate but this must be lodged within six months. An independent planning inspector will hear your appeal and his decision will be final. But you should think carefully before taking this route as it is very expensive and time consuming.
Instead, speak to the planning office who dealt with your original proposal as it’s possible there is room for negotiation. This might mean a fresh application to the planning authority but that will be preferable to a long and costly appeal which should be your last resort.