Beware!
Last time I took my watch (B1) to a Breitling dealer in Peterborough (in the shopping centre) they TRIED to con me that you couldn't just get the battery changed, it would need a full service which includes said new battery. Cost to me? £200 !!!!
Without doubt, the best place to go is Andrew Michael Jones Jewellers in Newark - he is Breitling's largest European retailer and is very RAF-friendly. He'll do the battery change at low cost and you should get a good service from him. He'll send the watch back to Breitling etc but will be more than consciencious re it's speedy return. Andrew is the guy who runs the Breitling hospitailty at Waddo airshow, amongst others.