@henno wrote:
The are no significant implications. But i would send an explanitory letter to the LA anyway with a revised commencement date.
Or just dig a bit of a hole where you are intending on doing the work and you have commenced. The only other involvement the planners might have is a request to see the foundations being poured but this happens very seldom and they will ring you for an approximate date anyway so you can just tell them there is substantial ground works to be carried out first.