Of course I'm a sibber which changes some factors but have a look at post #16 onwards in this thread...
Launching question West Mersea
The only real difference for you would be the need to take the vehicle/trailer away from the slip to one of the quieter village roads and leave it parked kerbside.
Otherwise the place has a lot of positives for a first trial run...
Hard packed slipway surface useable at 90% of tide states... excellent pontoon to immediately go to and make post launch checks... toilets/wash facility by pontoon... decent cafes... no slip or pontoon charges... plenty of boats about if you had problems with this trial run... even the RNLI adj the slipway!
We whoosh past you on our way to Mersea from Cambridgeshire... it would be an easy run for you.
Brightlingsea is another option. Slip has a fee to pay and it's very muddy when the tide is low which is why we avoid for sibbing but we do motor there from Mersea for the café. Decent pontoon, toilets & café etc. Better parking than Mersea just behind the waterfront.