I am trying to be positive and describe a way to do it correctly. Everybody tells us it can't be done.
If you get full planning then the only way for somebody to overturn it is to get a judicial review, which costs an absolute minimum of £20k and there is a 6 month deadline for it anyway. They also rarely succeed.
The planning system is chock full of cases where somebody got planning and then exceeded or varied what they applied for in some way. Somebody just around the corner from me got an enforcement notice served, because he got planning for a garage which was conditional on an old one being removed, but he kept both. I was in the planning ccttee meeting where the Cons councillor was practically banging his fist on the table demanding "immediate enforcement". Of course the Chairperson (being another Cons) supported him wholeheartedly.
You have to follow the process very correctly.