You get me too Birmingham in 2 hours!
Umm, not difficult from the centre of Cardiff - do it quite often in less.
LHR is the most conviniant airport by EK for the South of Wales
As a Gold Skywards card holder, I can assure you that LHR is not the most convenient airport. BHX is way easier. Also, the experience is much nicer at BHX (albeit the lounge isn't as good, but hanging around airports waiting for longhaul flights isn't my scene), the parking is a fraction of the cost and getting your luggage back doesn't take days.....
Back on topic -
Orly from Cardiff is great for getting to Paris, not so great for connections.... ah well.