Rachel.
Kanoni is the small peninsula on the East of the airport runway, you will see it on the right as you first touch down at Corfu. What you probably wont see is the small island that is linked to the land by a causeway upon which is the pretty little 17th century monastery of Vlacherna, you will probably already have seen pictures of this as most travel brochures show this when talking about Corfu. The reason you wont see it as you land is that you fly right over the top of it! People quite often mistake this island as being Mouse Island, but it is in fact Kanoni island and the peninsula gets it's name from that. It stands at the mouth of a lagoon which centuries ago used to be the main port for Corfu (you will see the lagoon on the left as you land) and the island was used to house the canons to protect the port – hence Kanoni.
Mouse Island (Pontikonisi) is just beyond Kanoni and is said to be the Phoenician ship turned to stone by an angry Poseidon after the crew defied him by returning Odysseus to Ithaca.
Not sure if you can get any trips direct from Arillas, ask Cerys or Noula when you go over to San Stef Travel, Noula has been running the business for years so if anyone can fix you up they certainly can. Otherwise you may need to get the bus to Corfu town and a taxi to take you to Kanoni (it's a bit far to walk). The taxi would no doubt drop you on the car park next to Vlacherna, there is a nice little taverna there that does a great plate of mixed fish and also sells the Arillas Brewery beer!
Google "Kanoni Corfu Pictures" – there are loads!