The programme, which runs until August 25, offers more than 33,000 sessions ranging from cookery classes to ninja club, and music lessons to horse-riding.
The majority of places (around 15,000) have already booked by families on benefit-related Free School Meals.
Councillor Zoe Nolan, Labour Progressive Alliance Cabinet Member for Children & Families, said: “It’s brilliant news that so many families have booked on to the Summer of Play already, as we’ve only just marked the start of the first week.
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"This is a brilliant programme which provides free childcare in a safe and enriching environment, alongside a healthy meal for the day. Last year, we created over 30,000 activity sessions and served 28,000 healthy meals – and it looks like we’re set to do even more this year.”
Councillor Jane Carr, Lib Dem Progressive Alliance Cabinet Member for Tackling Social Inequalities, added: “Inflation is at record-breaking levels, and the cost-of-living is going through the roof, so initiatives like this will make a real difference to families’ lives.
"There are people in Milton Keynes who have to choose between heating, eating and debt – so I know that free childcare, a fun activity and healthy meal will be a massive help to so many. I’d encourage families who haven’t taken advantage of the programme yet to book as soon as possible.“
The Summer of Play offers dozens of locations across the city hosting free sessions. These must be booked directly with providers with details available at www.milton-keynes.gov.uk/HAF.