OP, the rules on bringing a pet (cat, dog or ferret) into the UK are very clear from the link you provided in your original post. I believe you will need some time in France, to consult a competent vet, to ensure you meet the UK requirements. This is essential to avoid your cats being placed into quarantine. As BA is unable to provide the necessary veterinarian facilities to bring your cats into the UK, it is no surprise to me that BA is unable to respond to your request. Best to contact the rail company for info. Doc Copper (who has experience of crossing the Channel with a dog).