Parking at the Millennium Stadium Cardiff

[stoofur]

My friends and I are going to see a rugby match in September at the Cardiff Millennium Stadium. We have decided to stay in a Travel Lodge about an hour outside Cardiff. My question is. What is the parking like in Cardiff on a World Cup Rugby day? Or is it better to park elsewhere and then get the bus/train to the stadium?

I have never been to Cardiff before so any help would be really appreciated.