It was part of the Second Year Service for me.
I was surprised at it coming round so early.
Can't recall any such services on my previous cars, although only kept for 3 / 4 years at a time.
Anti Bac Cleaner: £10.21
(All excluding VAT of course.)
Saying that, it was also said that the Brake Fluid change was part of the Second Year Service as well, although some have said that this should start at the Third Year Service, then every two years.
Can't say that I've noticed anything at all with the AirCon Service (not expected to), although I'm content with the Brake Fluid Change.
Like tyres, I do like to think that I can grip and stop if / as necessary.