Interesting. Timewise it's pretty tricky, I did two Easyjet flights Newcastle-Bristol-Bordeaux over the Summer as going through London means having to change airports. Plus trains in England are expensive!
Edit: Trains in France are cheaper especially if booked in advance. TGV Paris-Bdx is three hours.
This does seem to be the best option actually. Need to do some proper planning, a return to Bordeaux is long overdue