@chuckpeterson The 30 hours is term time only, and is pro rated at 24 hours per week throughout the year.
There will also be the other additional costs such meals, additional hours at beginning or end of the day.
This is most likely the reason why the bill is still high, but I would 100% recommend asking the nursery for a breakdown of these costs and how they have arrived at that figure. Mistakes can definitely be made, and if there aren't any at least you will be more confident in what you are paying for.
Edit: Have removed my comment about hourly rate difference between nursery and government funding. It appears free hours means free hours, regardless of the nursery's hourly rate, although I will leave that for an expert to confirm