Colonsay is served by a Caledonian MacBrayne ferry service (www.calmac.co.uk) from the port of Oban. The journey takes two and a quarter hours and is a beautiful one, passing between the mainland and the islands of Kererra and Mull and then sailing South and West past the islands of Seil, Luing, Scarba and Jura.
There is also and air service that operates from/to Oban (Connel) that makes two return flights every week on a Tuesday and Thursday. Details from www.hebrideanair.com
The lodges are very easy to find. Go straight up the hill from the pier for 400 meters and the lodges are directly behind the hotel at the top of the hill.