The Greenwich Meridian runs down through the county of Sussex, splitting it in two. Thus, East Sussex and West Sussex are historically two distinct areas, both from a civil and an ecclesiastical standpoint, being run from Lewes and Chichester respectively.
Treating the whole county as one, the Sussex Family History Group can offer Parish Register fiche and CDs, plus Genealogy books and maps of the county.
Membership will ensure that a quarterly journal is delivered to you and, if you are local and able to attend, there are 6 meeting groups plus links to other Family History societies.