Anyone applied for planning after the fact?

[jaffajiffy]

I'm in Islington and in a conservation area. We read the guidelines and thought planning wasn't required for replacement windows at the rear of the property. We did get a building control certificate. Now thinking of selling and worried we will run into trouble. Has anyone thrown themselves at the mercy of the planners and fessed up later? Fwiw they were single glazed timber sash and we replaced with double glazed timber sash.
Solicitor says not to tell them and run it by a buyer then do indemnity insurance, etc., but id rather not have any negotiation if planning is easier.
Thanks in advance

When were the windows replaced?

We got an indemnity for exactly the same thing when we sold our last place. Cost something like £50.

Only in June!

Don't contact the council yet as you won't then be able to get insurance.

See what the buyer says and then approach insurer. Will probably be more than £50 because the works were done less than 12 months ago.

Ok. Good advice. Do you know the thresholds for councils caring about these things? Is there a rule about 12 months/4 years etc?