I would be super annoyed and just book something myself. If anyone asks, you can let them you know have x room and x spaces if someone wants to room with you. Not that you asked for advice on booking, but be wary of sharing a bed because most of the hotels are old and small so the beds are "full" or "double" so they are pretty small.
We stayed at the Pickwick last year and had to walk about a mile to the start. The hotel wasn't great and the parking was worse. You're right about booking right away. We booked rooms near the start in November. Congrats on getting in!