Three more things for consideration.
1. The range at which you can use "beams" for navigation is limited by the altitude of the aircraft. While the beams do not follow the exact curvature of the earth, Flying low level to avoid radar and AA could very well put the raiders below the altitude needed to pick up the radio signals.
2. It is one thing to slip an occasional intruder into a returning bomber stream, lack of IFF may be put down as an equipment malfunction delaying night fighter response. It is another thing to try sending in 12-24 plane strike forces and expecting the defenders not to notice or react.
3. a note on the increasingly unfriendly British skies.
a."...saw the number of enemy aircraft destroyed begin to rise steadily during the late winter and spring of 1941 - three in January, four in
February, twenty-two in March, forty-eight in March and ninety-six in May. It should be noted, however, that these numbers represented the combined figures for radar-equipped fighters and catseye's
day-fighters (Hurricanes and Defiants) operating in the night role."
b. "During February 1942, Beaufighters of Nos.29, 68, 141 604 Squadrons, were converted to AI.VII, with the radar enclosed in a 'thimble' radome developed by the Bristol Aeroplane Company"
I don't know if that is all the aircraft those squadrons or if they converted a few aircraft in each squadron as "trainers" with total conversion taking a while longer.
While German aircraft could operate of England in 1942 by night it would be without anywhere near the freedom they enjoyed in 1940 or the early Spring of 1941.