Kindly send me details of the number of children under the age of 4, split by town if possible, for London, Kent & Surrey.
ONS produces annual estimates of the usually resident population by sex and age across local areas of England and Wales. Whilst not containing population estimates for towns, the latest information on the population by local authority district can be obtained from the 2014 mid-year estimates table MYE2 which is available on the ONS website.
I have extracted a spreadsheet of population estimates for 0-3 year olds by local authority in the London, Kent and Surrey areas. This is attached as an Excel spreadsheet (see downloads associated with this release).
If you do need any help in finding population statistics please do get in touch with the Population Estimates Unit at firstname.lastname@example.org. They will be pleased to help you. It is not necessary to make a Freedom of Information request.