Normal setup is for Openreach to put in a 128 line splitter (4 trays, each one with a fibre back to the exchange and capable of serving 32 premises). They normally only have one tray live at a time and when that fills up, the next tray is prepared.
As Zarjaz deals with this stuff on a daily basis, I'm sure he can tell you what he sees now.
It's very likely that Openreach put in the infrastructure solely for you. The actual fibre cables are cheap, it's just the man hours that are the main cost factor. Even though you're the one footing the bill for building the network, it makes sense for Openreach to build the network for multiple premises.
Edited by AndyHCZ (Fri 10-Nov-17 16:43:43)