The Eurostar train takes just over two hours.
It will take about 1 hour and 20 minutes to get from London to Paris by flight.
Assuming there's still a direct flight from Paris to Cardiff, it should take not much more than an hour. Other options include flying from Paris to Bristol or Birmingham (or Manchester or Liverpool for North Wales) and getting a train or bus from there.
10 hour 10 hour
10 hours
about an hour-there are several airports in the UK/France so north UK to south France takes twice as long as say London to Paris.
Paris, London and Brussels
About 1 hour.
Take the 47 from london to paris.
Just over 1 hour
Just over an hour by train.
The journey from London to Paris by Eurostar takes around 2 hours 15 minutes. You then have to find your way to Versailles which should take roughly 45 minutes to an hour, depending on when the local trains arrive.
London St Pancras International - Paris takes about 2hr 15 min