Welcome to Appeals!
Appeals are basically the same everywhere as regards what you have to do.
All you need is explained in the Q&As:viewtopic.php?f=35&t=35032
I think all you have to know specifically with regard to Essex is that appeals for superselectives are hard to win!
Dutchy005 has written frequently about her experience. For example:viewtopic.php?f=35&t=31109&p=367941&hilit=normally+KEGS+appeals#p367941viewtopic.php?f=35&t=15949&hilit=dutchyviewtopic.php?f=35&t=14539&p=230463&hilit=dutchy#p230463