Went last year to San Antonio but as there were only three of us girlies, we didn't venture out very far. Want to find a decent beach this year so how do I get there? Bus, Boat etc. Also which beaches are worth a visit. Or should I just get hammered and live in my room? Comments etc. are much apreciated as i am useless and can't decide anything for my self.

Also, where are the cheapy cheap supermarkets for alkyfrol etc.

See Yall On the Beach x
You can get details on most of Ibiza's beaches from the main pages of this site, as well as details on how to get there by bus or taxi - you should try a trip to Playa den Bossa, though it's not the most beautiful beach on the island, it is big and clean, plus you have bora bora ;)
Hire / steal a car and head off to Cala d'Hort or Cala Jondal which are on the south-east-ish of the island, middle of nowhere and some amazing views and scenery to be had. Las Salinas (south-west-ish) is a nice beach as well.