Type the name in anyway.
Scroll down through all the possible matches:
As you can see, if you don’t like any of the matches, you can create a new school. But critically, the school is a topic. And it can be created and organised like any other Quora topic.
Do make sure you search for all the St Martins schools that appear as Quora topics, though. One of them might well be a match after all, and it might just be missing the right disambiguating suffix.