Does anything in the German text of the article in the
cdvandt site say what frequencies were targeted by the jamming? The British CH and CHL stations are known to have been jammed, but they were of limited use for plotting surface ships. There were, however, five Type 271 rdf (shipping) sets along the route and I haven't seen anything yet to confirm that they were jammed although most accounts claim they were.
By the way, there is at least one error in English AOB comments in the article on the link: German
T-boote were known as T-boats by the Allies, not E-boats.
T-boote were small destroyers (roughly equivalent to the Royal Navy HUNT class escorts), armed with torpedoes and 4" guns. German
Schnellboote were known as E-boats by the British, for reasons which are now confused.
Bruce