UL check in agent at CMB has checked in my luggage CMB - AUH on UL and then AUH - LHR on BA, both separate tickets on separate PNRs. The former was a revenue ticket booked on the UL website, and the latter was an award ticket booked with BA. Did not go through passport control/immigration in AUH.

Check in was at the Business class counter. You should be fine. The only exception is if the airport insists on passengers collecting their luggage and checking it in again.