If it's an issue that someone would know your address, then it's an issue that they would know your postcode.

If it's an issue that someone would know your postcode, then it's an issue that they would know your address.

I'm struggling to think of a scenario where you'd be fine with someone knowing one of those pieces of information without knowing the other.

It's not therefore an issue that there's a lookup between the two. Indeed you can do it trivially with google maps, or the plenty of other services that expose this database through their operation.

Any safety concerns aren't at the layer of translation between postcode and address, they're how someone tied either of those pieces of information to a given person.