I've been reading through the posts and trying to figure out the best way to get from CDG to Bath. The Eurostar looks good, but we'll be right at the airport so would flying be better? Thanks!
Look for flights to Bristol. In the England RS book they describe how to get between the Bristol airport and Bath. Apparently you need to catch a bus into Bristol, then train or bus to Bath.
What's your arrival time at CDG?
Go to www.skyscanner.com to see what's possible for both direct and indirect flights from CDG to Bristol.
Another option would be to fly British Airways from CDG to London Heathrow and take a National Express coach (highway bus) from there to Bath. If you book well in advance, BA's single (one-way) fares are competitive with those of budget airlines. Single tickets on Air France would be prohibitively expensive.
However, except for very long distances, I highly recommend trains over planes. Take the RER B from CDG to Gare du Nord, the Eurostar to London St Pancras International, either the tube (Circle line) or a taxi to Paddington, and a train from there to Bath Spa.
Both Easyjet and Air France fly nonstop from CDG to Bristol. Prices can go as low at 30 euros on Easy Jet.
From Bristol airport to Bath it's about an hour by bus/train.