I wish to build a brick built workshop in my back garden. I am allowed
to do this without applying for planning permission provided it built
within the rules of permitted development.

However my council want to bring my property within a conservation
area (this could happen within 7 weeks).This will mean that I will
need planning permission for the workshop.

How do I protect my right to build the workshop without applying for
planning permission (it will be refused when I am in the conservation
area) I don’t really want to start building it for another 18 months.

Thanks for any help you can provide

Bob