Does anyone know if I can catch a train to London from Cardiff Bay - or do I have to change?

I have caught trains from there in the past.

You can get one that goes to Paddington, but you may have to change somewhere down the line.

See here - http://ojp.nationalrail.co.uk/service/timesandfares/CDB/London/today/2100/dep

Where is Coogan?

Norwich?

No no Zach you can do cardiff bay all the way to Hong Kong, just a short wait while they change the wheel gauage at the border!

I thought the Bay line goes past the Clarence road station and through Lower Penarth and Lavernock - across the Severn barrage and into the Westcountry.

You want the line that goes through Roath, Marshfield and Llanwern stations.

is it worth getting any train to anywhere from Cardiff Bay when just down the road is the 'real' train station.....