Knowledge: depends on what you're looking for really. Hang out at North Weald and you may get a go in something exotic. There is no spamcan school or club there as it ain't licensed for training. There is one wheezy old C150 for rent from the Squadron, or for more money (and much more fun) the Bulldog and Pups already mentioned. The canteen and bar are very agreeable. Lots of fly ins, barbeques, talks etc.
A further point is that North Weald is a piece of living history: one of the oldest airfields in the UK, and one of the places upon which Churchill's "hinge of fate" hung and turned in the summer of 1940.
I've not flown out of Southend, just visited a few times (including first stop on my QXC: thanks kindly ATC bloke for writing up my dodgy landing as "good")so can't report on club, ambience etc. ATC service (now with LARS)always first class and an example to others.
Anyone mentioned Stapleford? Formerly a satellite station where the North Weald Hurricanes could take refuge whilst their Sector Station up the road was being pounded by the Heinkels, nowadays there's not
much in the way of interesting aeroplanes, and an irritating tendency of (some) local pilots (a) to fly circuits big enough to be seen from space and (b) to breeze through or near the North Weald overhead whilst positioning to join Stapleford, oblivious of North Weald traffic, but plus points are reasonable runways, a decent club house and a good pilot shop. Also the delights of Estuary English as she is spoke on the r/t.
[ 27 September 2001: Message edited by: FNG ]