Ask Lewisham Cyclists! They have an email newsletter, a yahoo group I think it is. The author of the midsummer night's ride thread on here, later that night, is a stalwart of it.
I'd take a guess it will include: Vicar's Hill, Blythe Hill, Honour Oak/O e Tree Hill, maybe Canonbie Road and Sydenham Hill.
Coolio, cheers!