I kinda like the idea. It would add another dimension to the game.
But can't you imagine the whines! You see this massive blob of an enemy attack on radar and everyone goes to intercept. All the friendlies reach the intercept point and there's only a single Lanc at 20,000 feet - while a real attack that was NOE went to a different base.
The only question is, was chaff used much, or at all, in daylight. Because, presumably, there were observation stations that tried to verify radar reports. At least during the BoB radar and observers were part of the British early warning system. At night visual observation would be difficult, or impossible, and chaff would be very useful. In the day, visual observation would not be so hard except when there was an overcast.
