The "NOT" bomber command, - i.e. naval-ops related had all sorts of aircraft in many odd places before there was area bombing in Germany.
We had all sorts of aircraft as far as up here in Iceland. Wellingtons included. As soon as 1940/41.
One of the first German U-boats to be captured intact was off the south coast of Iceland, some Cessna hour from where I live, - subdued by one 2 engined aircraft. I think it was a Douglas but would have to look it up.
BTW, when exactly did the area bombing start? 41 or 42?
British bombers started operating over germany by late november 1939. They never stopped operating over it until the end of war, except for the time the Bomber Command had to fly bombing operations supporting overlord preparations.
Bombings of german cities was already happening mostly since the war's start. Well, or at least tries to bomb german cities. Most british bombers in the 1939-41 time frame dropped bombs very far from target due to very serious navigation problems (they flew and bomb using star navigation).
Regarding radio guidance systems for british bombers. They were based on radio, but not the same as the german X-gėrat, Y-Gėrat or Knickebein (basically the german radio nav systems focused on the use of Lorentz beams).
Oboe was a very accurate system the british used to bomb german targets. In a given night, and for a certain target, two radio stations in england, with a large separation between them, were transmitting all the time. A british bomber with Oboe equipment had a transponder than when it received the signal, sent it back to the radio bases. The bases, calculating the time the signal had taken to go to the bomber, and back to the base, calculated the exact distance of the plane to the transmissor/receiver.
Prior to the bombing, the transmissors designed for the operation calculated the exact distance to the target between it and the transmissor itself. One of the stations "drew" a circle with the distance to the target, and the bomber navigated along that circle, at a constant speed and altitude decided in the mission planning. The other station "drew" a circle intersecting with the first one at the exact point where the bombs where to be released to hit the target given the plane's altitude and speed.
When the mosquito, flying along one of the transmissors "circle" crossed the other station's "circle", it dropped the bombs.
The accuracy was extraordinary. I don't recall the numbers by memory but the system had a CEP of around 100 yards at some 600km distance. When the system was re-made to allow for centimetric wavelenghts the accuracy increased quite a bit. Mosquitos with Oboe were as accurate, if not more, by night, than american bombers bombing in daylight using optical sights.
The germans didn't find out how oboe worked until it was already months in the use by the british. They tried to jam it, but by then Oboe was already using centimetric wavelenghts, and the germans never jammed this version.
There were more radio-guidance navigation/bombigs systems used by the british, such as Gee, but none was as successful as Oboe. And they even set up a system of beam-navigation analog to those of the Germans in 1940 to fly over germany, as a deception for the germans to lose sight on the radio navigation principles the british systems really used. Once the Germans realized it was a deception (late 1943), they stopped trying to jam the beams...and the british went on to actually use them for navigation until the war's end (and I think some of those stations are still operating today)
With all this advantages in precission bombing by night, Harris was still sending thousands of bombers to do area bombing until the end of the war. The conclussion to extract about Harris, is plain to see.