Thanks guys, was hoping you could get tickets on the TGV because last time we already had tickets but missed the train through a mixture of delayed flight, lack of sign posting from T1 and sheer stupidity. Had paid extra so that we could change the train if necessary but didn't realise that you could only change free of charge if you take an earlier train...bleah!
Carnets were what we were hoping for - have used them in Paris and found them really handy.