I found the info on Chickenpox in the AskBA system on their website (clicked on 'Contact Us'), and ScottC is right. Their official line is: "Information from British Airways Health Services states you cannot travel until six days after the last spot has appeared, and then at that point you will also need a letter from your GP/Doctor stating that you are no longer infectious."

Hope she's much better....they start feeling well very quick although their spots linger....