The Stranded — Christopher G. Nuttall

Centuries ago, the magic left our world ... and the magicians went with it, stepping into the Gates to Mystic Albion and leaving OldeWorld - Earth - forever.  Since then, the two worlds have remained separate, until now. Three young magicians, experimenting with dangerous spells, find themselves accidentally transported to the world their ancestors fled.  Finding friends and allies, they try to blend in as they struggle to find a way back to their home, unaware that danger lurks in the shadows of a very alien world ... ... And that they are already running out of time.