Laurence and Hisoka, I don't think it's a requirement that you have to cook something to go to the Potluck. I believe the whole idea of the potluck is to bring something for everyone to share and the main objective is to socialise . If you can't cook, just buy something from the shop or supermarket. Depending on how many people are going, find out who is bringing main dishes, snacks (appertisers), desserts, drinks etc.
If no one is bringing snack food and drinks, perhaps you can consider bringing along a few packets of chips like corn chips with salsa dips, a case of soft drinks (depending what people prefer to drink), biscuits & cheeses, fruits platter etc.... If there's no enough main dish, bring some Satay (takeaway) from the stalls or similar....
Hope the ideas help and don't get too stressed out about what to bring and just enjoy the gathering. I wish I can be there to try out the nice food people are bringing especially Mr Bear's popular braised duck.