Excuse me Graeme if I'm misunderstanding you, but what is the Philips 'digibox' receiving currently - satellite via Sky? The switchover you are referring to is the switching off of the analogue signal, so I don't understand how this could negatively affect reception via the Philips unit which I presume doesn't and cannot receive analogue signals, so the switch off is irrelevent in this respect.
Freeview is terrestrial reception via an aerial and is of course an option, but so is digital satellite via Sky or Freesat.