*Steps on soapbox*
It is against the law to market infant formula to new babies in this country. To get around this, the mmanufacturers have created 'follow on milk' with slightly different levels of nutrients and they can then call this a different product so they can legally market it. This means that their brand name is out there and if you decide not to breastfeed, they hope you will choose their brand. The formula which you give to a new baby is also suitable from 6 months and after one year. However after one year, a child is getting a wide variety of nutrients from their diet and their irone requirements in particular are lower. Cows milk does is a suitable drink (and it tastes much better) from one year and if your child is eating a wide variety of foods including fruit, vegetables, protein, carbohydrates and healthy fats, then they don't need any extra vitamins/minerals from formula milk. If there was a need for it, then your HV would have recommended it.
*Steps down from soapbox*