How do free hours work if DD already in nursery for full days?

[moggle]

I have asked my nursery about this they've been a bit vague, and as we're almost a year off from the term DD will start to get the 15 (maybe 30 by then) free hours, I don't want to bug them too much. So I'm just wondering about how other nurseries do it. DD is currently in for two full days 8-6, so 20 hours a week. We're in the SE and paying £73 a day, includes 3 meals and snacks, nappies, etc. Is it likely that we'll suddenly just start paying a quarter of our current bill?!! (seems unlikely, but I can dream!) . I'm guessing we may be charged separately for meals; or it may be that there's only a certain number of funded hours a day.
If you had a child in nursery before they were three, how did it change when they became eligible for free hours? If I can understand some likely scenarios I can do rough calculations on what'll happen to our bills next January. Hoping to be pregnant again soon and dreaming of giving up my boring part time job to do something else, so want to try and work out if it's even worth dreaming about until all kids are at school...

We got the 15 hours free so a day and a half free. Pay £2 on the full day for lunch and £2 a week for snacks.

Previously snacks and lunch were included.

Our nursery just took the free hours off the bill. Term time only of course.

In my experience, they just take the payment for the funded hours from the government & you just pay the extra hours (& any extras inc meals, nappies etc) at least that's what happened for us, although the nursery one of my friends uses still charge her for the 15 hours, even though they get the funding for her dc, but said they can still charge as it's a private nursery (although I'm not really sure how legal that is!)

Some nurseries will give you 15 hours free, so you would only pay for 5 hours - term times, so 38 weeks of the year.
Some will designate free hours, for example 9-12 are the free hours so in your case you would only get 6 hours free, term time.
Some nurseries will just knock off the funding they receive from your bill - however really they aren't allowed to do this, they should offer the actual hours free regardless of their charges. The funding from the council might be £3.85 an hour, so a couple of grand per child per year. This probably won't equate to you getting 15 free hours for 38 weeks.
You will almost certainly get charged for meals, and lots of nurseries also add charges for snacks and supplies too to try to make back some money.
Even if the nursery does offer you up to 15 hours free, you might find the additional hours go up in price - so £6 per hour normally becomes £8 an hour for additional hours to the funded ones.

Thanks all! I've just got a much more detailed response from the nursery manager and it's good news. I would be charged for 5 hours during term time, the full 20 hours during holidays. There aren't currently any extra charges for food etc. (But I wonder about what'll happen when it becomes 30 free hours - I know round here 3 days in nursery a week is a very common decision so this really would decimate their income).

It's really interesting to see the different ways nurseries implement it. It will help out a lot in terms of our cash flow. I guess now every extra month it takes to get pregnant I can consider it's another month with minimal childcare costs!