David,
Passengers take intermediary stops all the time, just as one example NQY to Scotland via LON, that's on a par with CWL/CDG via AMS is it not?
On the other hand could fart around with a bus or train in to Cardiff Central, then I guess another train to Bristol Templemeads, then a bus out towards some place called Lulsgate Bottom and, hey, on the return perhaps arriving back in to BRS at 2000 hours or whatever pne can look forward to getting home at somewhere around midnight.
Which sounds easiest to you?