Otherwise, I would pass N of Stapleford at 1400 ft, well outside their ATZ and keeping a very good lookout (an awful lot of UK GA flies at 1000-1500ft) and getting out of there really fast.
On a busy day you won't get a radar service out of Farnborough anyway...
Well, if you intend to do what you say, you'll have to talk to either Farnborough radar, Essex radar or Stansted to get permission to enter the transponder mandatory zone which is 'restricted airspace'.
