You are in a built-up area. Are you in this situation obliged to permit the bus driver to merge into the traffic?

Yes, because in a built-up area, a driver approaching a marked bus stop is required to enable a bus to rejoin the traffic. To do this, the driver must reduce speed and, if necessary, stop the vehicle when the bus driver signals their intention to pull out from the bus bay. This obligation does not apply outside a built-up area.