From today's obit:
31 Jan 43 Reynolds and Sismore led a small force of Mosquitos on the RAF's first daylight bombing attack on Berlin. (1100 miles round trip and as far into Germany as you really needed to go) . Crossing the Elbe at low level they climbed to 25,000 feet and arrived at exactly 11am when Goering and Gobbels were about to start a speech. The raid could be heard on the German radio that was to broadcast the speech live.
It did not say but one would guess they were VMC for the bomb run.
The 4000lb cookie was indeed a blast bomb and could be delivered from as low as 50 feet as attested by German Intelligence reports. Equally they could make precision attacks using smaller bombs. What they could not do was get the same weight of bombs on the target area as the main force, even allowing for many of the main force bombs not being in the target area.
For high speed low level ingress their nav kit was no different from the Canberra a decade and two later.