I must say though, it is daunting sorting holiday care compared to preschool childcare.
At baby age, you can use a nursery, you drop them at one place every day, you pick them up from the same location, it's open throughout the year (possibly only the week between Christmas and new year to cover), and if your childs key worker is sick, the office staff sort a replacement for you - the only cover you need is when your child is sick. All very straightforward, usually you can book your place as soon as you have your baby, can book what suits your commute, a year before you need it. Done.
School age, and suddenly not all childminders will go to the schools you need, some schools don't have enough childminders serving them, breakfast clubs can often not start until 8 (most nurseries will take children from 7:30 here to allow parents to be on early trains), and then with holidays, you need to make different arrangements with different providers.
It is tricky and provision is patchy. It's a range of different private businesses, without standardized practices or times.
It's not just a case of thinking about it before you have a baby, until your child is 4 you often won't know which school your DC will go to, so can't plan in advance like you can with preschool care.