I am unaware of any bus that crosses the English channel. As for driving, the trip will take roughly 22 hours (it is roughly 1100 miles). I would recommend flying unless you really need the car in Barcelona. (Barcelona has a good metro system, so you would only need the car to visit remoter villages in Barcelona Province.
Barcelona (BCN) to Cardiff (CWL)Flight Duration 2 hours 0 mins
4 hours
It is a long 6 hour drive from Madrid to Barcelona.
It takes about 20 minutes
3 hours 37 mins Harrworth Doncaster to Cardiff
It takes around the 7 hours and 25 minutes.
9 hours
The flight time from Bristol, United Kingdom to Barcelona, Spain is about 1 hour, 28 minutes.
A flight from Barcelona to Palma Spain is between 45 minutes to an hour. Many flight lengths depends when you leave from the airport and such.
217 mi, 3 hours 57 mins to Cardiff
Flight time from Bangor, Maine to Barcelona, Spain is seven and a half hours.
6012 miles only