On this side of the pond our schools do not have numbers, so it is a hard question to answer.
It is possible, although rare, to refer to places by number. For example here our municipal political districts are numbered, so I might say "I live in District 3", but since the districts don't have any relevance beyond local elections which people don't really care about anyway, it's not a common thing to say.
Another way we might refer to place by number is in a large office complex with multiple buildings. So I might say "I work in Building 3." But this too is unusual; I would only use it when the building cannot be identified either by the name of the company or its street address, and the number of situations where that would happen is very very small in this part of the country.