Dana Centre, SW7 5HE
The Dana Centre in South Kensington is essentially a spin-off of the Science Museum. It hosts an extensive schedule of free talks and discussion sessions, designed to make science more interesting and accessible for adults.
The event list is available on their website, as are contact details (tickets must be booked in advance although they are free).
Bus routes ? and ? stop just down the road ([Queen's Gate]?). 74 stops nearby further down Queen's Gate (towards Putney) or on the [Cromwell Road]? (towards Hyde Park Corner). ? stops in Stanhope Gardens, and any of the routes serving South Kensington station aren't too far away.