There is some confusion around lactose and the low FODMAP diet. People often assume that when following the diet that they cannot have any products with lactose. This is not the case. Lactose is a disaccharide sugar which is present in milk and dairy products in varying amounts. When following a low FODMAP diet unless you have been diagnosed as being lactose intolerant then you can have lactose in limited amounts. For example you will see on the low FODMAP chart that yoghurt and crème fraiche in addition to many cheeses are acceptable.
Some people find it better just to eliminate lactose altogether certainly during the restriction period. If you are unsure about the lactose content in dairy foods check whether they are suitable on the Food Maestro low FODMAP APP.
Nowadays there are many lactose free alternatives that are low FODMAP from example, oat, hazelnut and rice milk. Arla also have a range of lactose free products.