The UK is divided into 12 regions. Each region has between three and ten Members of the European Parliament (MEPs) and each MEP in a region represents each person living there.
There are ten MEPs for the South East Region, which includes West Sussex. You can find information about each MEP's recent activities on the European Parliament website:Access the European Parliament's website for the South East Region (external link)
Each MEP has their own specialisation and interests and sits on different parliamentary committees. The MEP you need to contact therefore depends more on the issue than their location.