I submitted an application to the local council for a single storey
extension within allowed limits - only so I could have a 100% rubber
stamp that it was permitted.

As the application is public info I've now received a letter from some
party wall surveying firm warning me of complications of this and
that. They've also kindly sent letters to my neighbours - how nice of
them!

Now, obviously these **** stirrers find this a good way of scaring
people and making money but where do I stand? I know I have to give
notice to neighbours but providing works are done to a satisfactory
standard can they stop me from doing it?