The problem with the 'British standard' breakfast of cereal and milk is that it tends to be high in sugar and processed carbohydrates and low in protein. Even if you go for a wholegrain muesli, it's glycaemic index value will likely be very high, meaning that sugar levels will spike quickly, followed by an increase in insulin, setting you up for a day of fluctuating blood sugar and increased hunger.
Jordan's cereal for example contains 9.2g sugar per 45g of cereal, sugar is the largest ingredient on the list after the cereals. Even Bran flakes and Weetabix contain sugar as the next ingredient after wheat or barley. Bran flakes also contain glucose syrup. And these are cereals which are often considered to be the healthy option!!
Alpen contains 9.5g of sugar per 45g so it is 21 % sugar (Coco pops contain 5.1g sugar per 30g of cereal so it is 17% sugar)
An easy substitute for sugary cereals is yoghurt and fruit which I usually have as an option on the client's food plan. Yoghurt is a good source of protein, you will need around 160g of natural yoghurt balanced with around 100g fruit for a good slow release of energy.
Yes there is sugar in the fruit but it is a natural sugar which is very different from added sugar. Going for low sugar fruits such as berries is better, alongside a good portion of yoghurt gives protein to help
Goat's and Sheep's milk yoghurts can be better tolerated by some people and tend to be less likely to cause an immune reaction as can happen with cow's products. Organic is always better with dairy. Other alternatives are sugar free Soy yoghurt or coconut yoghurt.