JICPOPS UK population estimates for 2016

Total population     65,465,687
  Adults   53,814,772
    Men     26,309,281
      aged 15-24     4,071,319
      aged 25-34     4,467,815
      aged 35-44     4,122,367
      aged 45-54     4,534,765
      aged 55-64     3,728,421
      aged 65-74     3,125,552
      aged 75+     2,259,042
    Women   27,505,491
      aged 15-24     3,896,923
      aged 25-34     4,422,421
      aged 35-44     4,181,500
      aged 45-54     4,675,935
      aged 55-64     3,846,406
      aged 65-74     3,359,371
      aged 75+ 3,122,935
  Children     11,650,915
    Boys aged 0-14     5,965,387
    Girls aged 0-14     5,685,528
Total households     27,731,938

Data with population, households and demographics within postcode sector are available from CACI