Thanks for your responses - much appreciated.
Update for those interested.
Took it to the VW service garage and they recalibrated the sensor 'under warranty' without any questions. Not sure if this is due to the noise I made prior to dropping the car off but nevertheless, glad it didn't cost me £350.
They didn't clarify whether it was loose or the reasoning behind the fault so assume it was a fault on their part during the 1st service visit a few week ago.
Got the car back last Thursday and so far so good until this morning. Driving along the road when I get a new warning message saying 'Front sensor impaired, ACC & front assist not available'.
Not to be confused with the previous message which was just said 'Front Assist unavailable' - no mention of sensor being impaired.
Pulled over and wiped the front emblem thinking it may have been bug splatter. Switched the car off & back on and hey presto - no warning!
Going to report it to the garage regardless so they have a note of it however hopefully won't reappear. All the snow we've had the past week has cleared as of yesterday so can't even put it down to that

Fingers crossed!