The Bristol Bombay had a range of 3589 km with maximum fuel and no load. The Bombay could carry 2000 pounds of bombs when used as a bomber. Does know the range of the aircraft when armed with the bombs?
My "Aircraft of the Fighting Powers" gives the maximum range of the Bombay as 2230 miles, which agrees with your 3589km, so there's some consistency to start. the fuel load is given as 925 gallons, or 6785 lb. Assuming you trade 2000 lb fuel for bombs, then you are down to 70% fuel. Since you will use the same amount of fuel for takeoff and climb, I would think the range would be about 55% of its maximum, or 1975 km.
Hope this helps,
I'm not good at bombers but as I remember the max range of the bomber,I mean 3589km ( other source 3588km) it was with additional fuel tanks.Without them the max range was 1418km.
In addition I've found this info:
Range w/max.fuel 3500 km - 2175 miles
Range w/max.payload 1400 km - 870 miles