Yes, but you must do it within 12 weeks (if you are appealing as a householder) or six months of your original planning permission approval. Your appeal goes to the Planning Inspectorate, and you need to be able to argue that the condition or conditions are unfair, unreasonable, or unlawful. But the appeal process can take up to six months, and you can’t start building work during that time. And because the Planning Inspector will examine the whole of your original planning application, you can lose your planning permission altogether.