A baby can travel from one week for a short-haul flight and three weeks for a long-haul flight.
Permitted products: medicines and foods that your baby needs without restriction or prescription.
Regulated products: 100ml maximum for liquid care products (such as lotions) placed in a 20cm x 20cm clear plastic bag.
Baby food: remember to take resealable containers: you may be asked to taste these foods during security checks. As for quantities, they should be "reasonable" given the length of the journey.
Practical advice
To alleviate the effects of pressure changes in your baby's ears, give him a bottle of sugar water.
Take-off and landing are stressful times for your baby. Reassure your baby by chewing on a dummy or breastfeeding.
Take along a blanket and toys to calm and occupy your baby during the flight.