Our Slovenia guide is a work in progress at the moment. But do take a look at our Moving to Slovenia page for an overview of expat life.
I am a British expat living in South Africa and there are a few sites that I can recommend. Internations is a global network for expats and they hold monthly meetings and events in cities all over the world for expats. Another good website is meetup.com - you can find groups focusing on particular hobbies and interests, which will allow you to meet like minded people.
I would also suggest seeing if there are any local book clubs or sports clubs you good join - these are a good way to network and make friends.
Best of luck in Slovenia.