Hi..Well..not much in actual Southend...I sometimes have a quick poodle around Priory park, normally when I've just put something new on the bike n needs a quick test. Nearest rides are prob follow Progress Road off the A127 then up Tudor Road and into the wooded bit there, there are a serious of dirt jumps near Brook Road I believe and it you keep on going across a field or two it joins up with Hockley Woods where a few people ride.
Other nearest ones are Hadleigh Castle area (I tend to jump on a train to Benfleet and ride a route with max DH and minimum uphill (coz I'm lazy) and ride to Leigh.
Ive got lots of routes saved, I use Endomondo to track em using GPS on my phone, you can goto the wensite
http://www.endomondo.com to view them, my user name is andy dee, think you may have to register as a user first.
Ive attached one.
Andy