The Castle Leisure Centre is to open its doors in April 2016.
It will be located on Gabriel Walk and will provide a six-lane 25-metre swimming pool, a learner pool, a four badminton court sports hall, fully equipped gym and indoor cycle studios, two exercise class and dance studios, a crèche and cafe.
The council will operate the £20 million Castle Centre in partnership with Fusion Lifestyle.
Councillor Barrie Hargrove, cabinet member for public health, parks and leisure said: “We are confident that the fantastic facilities will be worth the wait."
"We've already surpassed one degree of global warming," said Kristen Buida, manager of the London Climate Change Partnership.