Because of its location, Cardiff is a little isolated. However, there are regular rail services from most place in the UK. The nearest airport is Cardiff International
Airport (12km) which has regular flights to Amsterdam, Brussels and Paris, and weekly direct flights to the USA and Canada. National Express operate a reasonable service. Road links from England are via the M4. If coming by road, make sure you use the Clifton Suspension Bridge, which is pretty impressive.
Train Timetable for Cardiff Central Train Station Cardiff International Airport Road Map (pdf format) Cardiff Bus UK Bed and Breakfast