With an ADV service you need a minimum of 2 controllers unless you do 2 hours ADV followed by 30 min A/G; with A/G only you need someone to monitor the radio and answer it when necessary but the controller on his mandatory 30 min rest break would not be allowed to do it as this break is conditional on not performing any ATS or A/G related activity.
Any reduction from the services notified in the AIP would have to negotiated with and approved by the CAA and they don't normally approve a 'mix' of services every day.