Bring a large frying pan with water to the boil. Add the chicken pieces and poach for approx 7 minutes until cooked through. Drain and set aside to cool.
In a food processor, combine the cheese, yoghurt, lemon zest, mustard and seasoning. Stir through the herbs and celery.
Fill the bread with the chicken mixture and rocket leaves.
Note: The use of the preservative calcium proprionate in bread (282) to inhibit mould is linked to behavioural and learning problems, migraines and asthma.
For that reason alone you should always check the ingredient list when buying bread or invest the extra to buy a great quality wholegrain sourdough from a reputable baker.