I live relatively close to Stratford and can reel off the number of groups off the top of my head in the local vicinity.
I think Earls Cone would be a good bet also..last time I checked £65 a month to fly C172 and C150 (under 100 hours) and then add the PA28 Archer 2 (over 100 hours P1)- but you need a car to access it - there are a number of groups/individual operators based there.
Stapleford has a share in an AA5 for sale (not for me) but maybe for you and they are replacing their fleet with new Technam's at £136 per hour (if I remember correctly - been a while since I been there).
Southend has "Seawing" Airclub which is a private members owned club. Not sure about commercials. Southend Landing fees are a bit steep... £23-26 from memory.
FYI - I do not belong to or sell any of the services of the above but it is important that you find something which works for you.
I am planning on making a visit to Damyns Hall so would be interested myself also as to what is based there..
Hope this helps.
Scoobster