Try an experiment:
Unplug the fridge/freezer. (You're food will be fine for several hours if you keep the doors shut). You might find that your lights stop flickering. i.e. it could be a fault with the freezer which is causing intermittent excess current drain (at the same time as it makes a strange noise). That, in turn, could be leading to your lights flickering. If so, it would be pointless to pay an electrician lots of money, to spend hours checking out all of your electrical circuits, if the fault lies with the fridge/freezer!
If your lights still continue to flicker, with the fridge/freezer unplugged, then either there's a poor connection somewhere (which could lead to a fire risk through sparking) or current is somehow managing to find its way to earth without tripping the circuit (which could lead to a fire risk through the wiring overheating).
Chris