OP, Lee valley bike park on your doorstep, canals and river Lee both rideable either up to Epping or down to Woolwich Tunnel and across to Abbey Wood.
Small pump / BMX track in Mile End park, bigger one in Hackney.
Train from Stratford will take you to Benfleet, and then to Hadleigh
Hog Hill / Hainault park has some riding although not been.
I’m out a few times each week, on a MTB and live down by Canary Wharf. Email in profile if you want to get in touch? Whatever you do, it all needs a bit of peddling !!