96 Seat Ibiza battery connection

My car died this morning, I was in a petrol station putting air in the tires and went to turn on the engine, car started but instantly cut out, from then on there was nothing, no lights no radio, no dash clock, so I think its the battery. I open the bonnett and take a look. I notice 3 connections to the battery, the + and - terminals and then another connection, the "other" connection looks badly corroded, there is what looks like blue chalk around the connection. I dust away the "blue chalk" and the cable connection to the battery detaches. I now have a loose cable and what looks like a corroded connector. Is it just a case of buying a new connection and reconnecting this loose cable to the battery or is there something else up with the car.
I had to leave the car in the petrol station and get the bus into work.
Any ideas, I am right in my assumtions?