I have just added this to the UK Map of places to fly your Drone at https://dronescene.co.uk
From Manor way there?s public foot path which will take you to abandoned pier. Area around can be used for take off.
Be careful and watch for private land and restricted access.
Thanks @goga999i for the recommendation, I went here today, as suggested parking at Manor Way, which is free and next to a cafe and a breakers yard.
From here, the exact location of the public footpath entrance is ///resist.split.always
The path is very muddy and swampy, I’d suggest wellies or a decent pair of waterproof boots, I didn’t today and regretted the decision 
All the same, relatively secluded place, few bird watched bumble by occasionally. Be careful of the national grid and definitely wouldn’t take the risk flying if there’s too much wind as a very open space.
Here’s my video from today, could have done with more blue skies but the place to shoot is fantastic.
It’s great to hear people reporting back on recommendations from others - makes Drone Scene very worthwhile 
This is great. Somewhere to fly near london. Thank you.
Credit to the op for pointing me in this direction, just realised I posted wrong video above and it won’t allow me to edit for some reason.
Here’s the correct one
