zuz
Speaking as a controller in the LTMA - Sat mornings and sunday afternoons can actually be fairly busy - although you have less internal flights (businessmen going from say Gatwick to Glasgow), there are a high number of 'holiday' flights.
Another factor to be considered is that when there are actually less flights around, we will bandbox sectors. Sometimes this makes the frequencies seem busier as you will hear transmissions from other frequencies that you do not have selected in the cockpit (because we cross couple them) - though in truth the workload for the ATCO will be no more than a normal steady day