It depended on what they expected to meet. "Milk Run" was for an easy target. After that, I'm firing blanks.
The British Radar, invented by Watson-Watt I think, was rather good. Before the war started, the Germans sent the Graf Zeppelin or the Hindenburg on a recce mission. Whatever dirigible it was, they dropped a wreath in the middle of Yorkshire for some reason, but the mission was to probe Britain's defences.
The Germans had Radar too. But they gave it away by codenaming it... Heimdall, I think. In Germanic mythology Heimdall, if it was he, could see a 100 miles in darkness. Which soon had us plucky chaps forming Commando groups and investigating strange radio installations.
There's a hell of a tale to be told in those missions. But, I'm really drunk. So you'll need to Google it yourself.
Regards