Hi Charles,
As an Essex resident (not native, as you know) I've always struggled to find somewhere that appeals to my eye. However, Paul Mitchell has recommended "Heybridge Basin", which is just outside Maldon. I've visited maldon several times and I'm certain there's some great shots to be had but I struggle to find them. Maybe you'll have better luck?
Walton, Frinton and Clacton are all places I've visited a few times but come away largely, empty-handed. Jaywick is, apparently, the most deprived area in the whole of the UK - largely a shanty town of former holiday homes gone to ruin - but some intersting sights. I've been a couple of times and it is rough. I don't recommend you go after dark.
If you go up the Suffolk coast, Aldeburgh and Southwold are a lot more appealing, in my opinion.
