National Express run direct coach services from most major towns and cities in Britain to Devon and Cornwall. You can buy a Britexpress Travel Card or Tourist Trailpass before you depart, or on arrival in Britain.
There are also coach companies based throughout Europe who operate tours to Devon and Cornwall. Your local VisitBritain office will be able to provide you with details. Alternatively, you can book with a British coach company once you arrive in Britain.
www.nationalexpress.com