Varna Airport's website has been 'revamped' and now only shows live arrivals & departures - however the Burgas Airport website does show a BH Air arrival from Manchester, as below:
19/06 23:00 Manchester [ Ringway ] BGH5512 B H Air
The Manchester Airport website merely shows "There are no scheduled flights from Manchester Airport to Bourgas Airport" on the 19th June.....
Baldur