MAN, like you say, is always quiet this time of year a scene which is replicated at various other UK airports. The place livens up during the peak periods but empty stands and quiet terminals at certain times of the day and at this time of the year is nothing new. Last year for instance whilst waiting for the lunchtime EK there was only one other flight (LH) departing around the same time.
ZB is now in T2, LS have always practically parked much of it's fleet over Winter and Easyjet have incredibly quiet days during mid week at this time of the year.