You could reduce the cost by taking a budget airline flight to Paris but you'd still have to pay �454 per person from CDG to Genoa. (Additionally, if your budget flight was cancelled or delayed, you'd not be able to claim any compensation in respect of missing the Air France flight).
The Genoa airport schedule shows that Air One operates from both Naples and Rome Fiumicino to Genoa. (Alitalia also operates on the Rome FCO-Genoa route). Thomsonfly has a scheduled service from Manchester to Naples. Jet2.com operates from Manchester to Rome FCO. There are no flights from Liverpool to Naples. Ryanair fly to Rome, from Liverpool, but they use Ciampino airport.
Jet2com are currently only accepting bookings up 25th Oct but, based upon the fare for 20th Oct, they'll fly you to Rome FCO for �19.99 (That's including taxes!). Air One have several flights per day from Rome to Genoa, at �72.56 (about �50) per person. So, I recommend flying Manchester-Rome-Genoa, with Jet2.com and Air One, for a total of about �70 per person, including taxes. Why not have a few days in Rome, if time allows? (Genoa is also a great city to explore. The Old Town is really lovely).
I'll post this lot, then I'll take a look at flights from Cape Town.
Chris