My boyfriend and I have just started getting our 2 and half yr old to nursery and it's going great but..?

It is common practice for daycares to charge even when the kid is not in school. They charge to hold his place, otherwise they have to allow a new kid to make up the loss in revenue and that child takes your child's place. Its how it works. Remember, daycare is a business and they also need to make thier money and pay their creditors and employees so they will continue to be there when you are unable to be.