JICPOPS UK population estimates for 2019

Total population     66,850,161
  Adults   54,820,344
    Men     26,852,781
      aged 15-24     3,985,995
      aged 25-34     4,554,885
      aged 35-44     4,176,286
      aged 45-54     4,464,423
      aged 55-64     4,009,553
      aged 65-74     3,221,267
      aged 75+     2,440,372
    Women   27,967,563
      aged 15-24     3,776,080
      aged 25-34     4,479,287
      aged 35-44     4,241,144
      aged 45-54     4,595,583
      aged 55-64     4,153,663
      aged 65-74     3,472,558
      aged 75+ 3,249,248
  Children     12,029,817
    Boys aged 0-14     6,163,457
    Girls aged 0-14     5,866,360
Total households     28,005,071

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